Judging A Side Over One Season.

For much of Alan Pardew's reign at Newcastle, his side has provided ample topics of discussion for the analytical community. Their fifth placed finish in 2011/12, with a goal difference of just 5, was widely seen as the product of a decent side getting a bit lucky and their near relegation the following season merely served to reinforce some misconceptions that exist around luck based over-achievement immediately snapping back into ledger balancing under-achievement.

This season the team has largely occupied the dead ground between Simon Gleave's Superior Seven and Threatened Thirteen. They currently hold 8th spot with very little likely up or downside, casting them as mere spectators to the title and Champions League tussles and the relegation grind. So it has been left to their off field employees to guarantee column inches.

Over the previous two and three quarter seasons, Newcastle's success rate, that counts draws as half wins, has averaged out at a shade over 50%. If the Premiership were allowed to meander on without a season's end reckoning, Newcastle since the start of 2011/12 have recorded results typical of a side finishing a 38 game season in 8th or 9th spot, with a goal difference in the region of zero. So, despite the bouts of squad strengthening and weakening during the various windows, might Newcastle have been broadly a "best of the rest" team under Pardew and has their seemingly up and down seasons simply been down to talent and luck interacting in differing doses?

Simulating season long results for one side or a whole league can quickly produce the range of possible outcomes we might expect from teams of a certain quality and it is perhaps a sobering thought, especially for managers that there is a non trivial chance that the best side from the Threatened Thirteen could find itself struggling to top 40 points over a 38 game campaign.

There is almost a 10% chance that a side with a true success rate of 0.5 may recorded 41 or fewer points, the limit of Newcastle's achievement in 2012/13 and a 6% chance that they could rise to the highs achieved in the previous season.

So although a dissected break down of Pardew's previous two completed seasons would give an entirely factual record of the points per game performance of his side in the 2011/12 and 2012/13 seasons, we can be much less sure if that see sawing record accurately tracked the talent of the team.

What we see, isn't a cast iron endorsement of quality or the lack of it, but a combination of randomness and talent.

It would have been easy to over react to the raw results posted by Newcastle in either season and while injury, Europa League involvement, squad churn and tactical change almost certainly impacted on their talent and luck based achievements, it seems unlikely that the 24 point difference between the 2012/13 team and the 2011/12 team truly expressed the quality gap between those two closely related editions of the side.

One way of trying to reconcile an apparent points based performance improvement to any real shift in a sides actual abilities is to utilize to expertise of the bookmaking industry. At the start of the season all of the spread firms publish the expected number of league points they think each side will gather by the end of the season. As the season progresses these estimates will be up or downgraded in line with each side's current rate of accumulation of points.

For example, prior to last Saturday's eventful head to head meeting with Newcastle, Hull had already posted 31 points, almost equal to the general preseason estimate of around 33 or 34 points. Their updated quote suggested they might get about 42 points. So from a performance perspective they were roughly 8 points ahead of where most bookmakers expected them to be.

We have also reached the second half of the season, where a side increasingly completes their head to head appointments and by mid March a team has played a rival home and away between 9 and 11 times. The chances of a team winning or drawing a game depends on not only the gap in quality between the teams, but also the venue. So the expected success rate in a return fixture will depend partly on how each team has progressed or regressed over the 190 or so days between the initial meeting, but also where each match was played.

Above, I've plotted the pre-game quoted success rates for actual Premiership matches, paired by home and away matches. So a home side that is expected to have a 60% success rate at home would likely be quoted at around 40% when they traveled to complete the reverse fixture.

If we look at the actual differences in the quoted success rates for return matches any deviation from this fairly strong, general relationship can be, at least partly attributed to the direction both sides have moved in over the ensuing timescale.

The case of Crystal Palace (or more accurately, Tony Pulis) demonstrate the process. Up until March 19th, they have played 10 teams twice. Stoke, Hull, Manchester United, Norwich, WBA and Southampton each made a return visit to Palace and Palace set off to reacquaint themselves at the homes of Arsenal, Spurs. Sunderland and Swansea.

In eight of those ten matches the quoted pregame success rate in the return was greater than predicted by the success rate in the initial game and the line of best fit from the plot above. Palace's quoted success rate posted by the bookmakers is on average 15% higher over the ten rematches, compared to a typical example from the line of best fit. In short, the recent quotes imply a level of improvement compared to Palace in the opening months of the season.

There are strength of schedule issues, Palace may have played ten teams whose true ability has dipped, but this can be addressed by a least squares approach to the overall loss or gain in success rate of each side, when measured against their actual repeat schedule. The order shuffles slightly if you apply this correction.

Which Teams Have Impressed Enough to be Upgraded from Preseason Estimates?

Team.	Average Shift in Success Rate per Game.
Crystal Palace.	0.06
Liverpool.	0.04
Hull.	0.04
Arsenal.	0.04
Manchester City.	0.04
Chelsea.	0.03
Everton.	0.02
Newcastle.	0.01
Sunderland.	0
Southampton.	0
Manchester U.	-0.01
Spurs.	-0.01
WBA.	-0.02
Norwich.	-0.02
Stoke.	-0.04
Swansea.	-0.04
Cardiff.	-0.04
Aston Villa.	-0.04
Fulham.	-0.05
WHU.	-0.06

The table above shows the strength of schedule corrected, average raw success rate increases or decreases per game as seen in the repeat fixtures played so far by each Premiership team. It's a combination of perceived improvement (Liverpool) or decline (Manchester United) and partly a popularity contest.

Stoke are on course to better most preseason points estimates, but their marmite factor makes them a universally unpopular team, which may account for their apparent downgrading, despite a better than expected transitional campaign. Even punters have to be offered inducements to side with Stoke! But hopefully, most sides in the table have been up or downgraded predominately on the bookmakers interpretation of repeatable form.

To add context to the previous table, I've finally plotted the change in pregame quoted success rate against the rise or fall in expected final league points totals compared to the estimates at the start of the season. Fulham, for instance are on course to be 10 points adrift of preseason estimates and they've been downgraded by an average success rate of ~0.05. Slightly more than you would expect from the plot.

Palace are on course to gain about 36 points compared to the 31 quoted in August, but their position, well above the average line appears to reflect extremely well on current manager, Tony Pulis and less so on Ian Holloway, who was in charge for the bulk of 2013. Pulis, once again demonstrates an ability to turn relegation fodder into lower half scrappers who can take their season to the wire. When he was appointed Palace had 4 points from a possible 33 and were rock bottom.

Steve Bruce's tenure at Hull is also endorsed by the betting movements. Not only were the Tigers underrated, but there appears cause for added optimism above and beyond there current position of relative safety.

Both Merseyside teams have gather more points than expected, but Everton's upgrade still lies below the line of best fit, possibly indicating a reluctance to take their improvement wholly at face value. A caveat that also applies to Southampton.

Liverpool may be the most telling point on the plot. They were expected to gather around 66 league points when the season began, currently they may be able to top 80 points. An increase of around 16 points. However, if we roughly apply their average increased success rate that is currently being applied to them over a 38 game season, their points total increases by just around half of those 16 points. Outstanding, but partly unexpected performance isn't being taken at face value on a match by match basis. It is also being taken with a slight pinch of salt.

The Reds' uptick is as spectacular as the 38 game epic demonstrated by Newcastle, when they nearly claimed a Champions' League spot, but it may be well to remember that single season performances are a product of repeatable skills and also less repeatable variation. Even with points in the bag, a team might not really be quite as good (or bad) as their record might indicate.  

Red Cards and the Big Four.

The win probability for each team is tracked on a minute by minute basis throughout each game.At any point in a game a team will have a probability of winning the game outright and an associated probability of drawing the game.By multiplying the probability of winning the game by 3 and the probability of drawing by 1 and adding the results together you will get an expected longterm average for the number of points that team will achieve from that position or Expected Points (EP) for short.

Every football fan can remember games or incidents within games that are especially significant for their club.They usually signify that their team has reached a new high in it's development or plummeted to new and possibly permanent depths of ineptitude.Stoke fans would probably put November 1st 2008 into the former category.The initial 45 minutes of their first EPL season where they shipped a goal every 15 minutes was still a raw and recent memory,but they had partially steadied the ship with wins over Villa,Sunderland and an obliging nine man Tottenham.They occupied 15th place in the EPL,the average finishing spot for promoted teams in their first year in the higher grade,but defeats at the hands of Bolton, Middlesbro', Everton, Chelsea, Man City and Portsmouth meant that the visit of third placed Arsenal to the Britannia was a daunting prospect for the hosts.

Pre game expected points values made the Gunners huge favourites.They would expect to return with an average of 2.34 points from their visit north,while Stoke would be lucky to average half a point a game.

However,today was a day when one of the least favoured scenarios materialised.Fuller's 11th minute strike would rarely have been a decisive first goal and Stoke had to maintain that lead until after the half hour before they became the team favoured to clinch more points on average from that particular game situation.By the 70th minute Stoke still held the advantage and would be expected to gain an average of 2 points per game in such circumstances,but they tightened their grip three minutes later when Olofinjana stumbled his way into the box and bundled a trademark Delap throw over the line.Instant cult status for "Seyi".

Scorers;
1-0,Fuller,11'(Delap assist)
2-0,Olofinjana,73'(Delap assist)
Red Card,van Persie,Arsenal,76'
2-1,Clichy,90'

If Arsenal had been unaware of their underdog status from the half hour mark onwards,they certainly knew their likely fate now and three minutes later their predicament worsened even more.Stoke's keeper Thomas Sorensen deliberately dallied over picking up the ball in his box,inviting the loitering van Persie to participate in a game of cat and mouse where the Dutchman was by far the junior partner.Van Persie's half hearted lunge for the ball was never going to arrive before Sorensen claimed it for himself and what the subsequent shoulder charge lacked in violent intent it certainly made up for in stupidity.Sorensen collapsed in a heap,although he was careful to remain in front of his goal line and Stoke's favourite referring pantomime villain,Rob Styles set van Persie packing with a straight red card.The dismissal left Arsenal in a hole too deep for even a team of their attacking flair to emerge from and Clichy's 90th minute strike was merely a consolation.

The view  from the stands confirmed Stoke as a team who could compete on their own turf with the league's very best,dreams of a European Tour were a few seasons down the road,but the Potters were no longer considered to be a team out of their depth.Regarding the dismissal,it was difficult not to conclude that van Persie had reacted to the situation of trailing and most probably losing to a team who should have been dispatched with the minimum of fuss and in a manner Chelsea had achieved on the same ground a month earlier.It was a clear case of red card bourne out of frustration.

It's easy to attach too much importance to individual events,so to test the theory that the best teams see red when they fail to reach the heights they generally attain,I recorded all games involving the Big Four,Liverpool,Arsenal, ManUtd and Chelsea where a red card was shown to their players. I charted the pre game Expected Point Values and the EP for the team in the minute before their player was dismissed.Games between the big four were removed from the sample.

Games against inferior opposition where the big four received a red card.2004-2011.

Teams.	Number of Red Card Games.	Average EP at Kickoff	Average EP just before Red Card.	Average % fall in EP	% of Games where EP fell before Red Card.
Man Utd.	12	2.02	1.54	24	75
Arsenal.	15	2.09	1.73	17	67
Chelsea.	16	2.29	1.98	14	56
Liverpool.	6	1.83	1.01	45	83
Overall.	49	2.11	1.68	20	67

As can be seen the average Expected Points just prior to the red card are below the average EP at kickoff both for the big four as a group and for each individual team.The EP fell on average by 20% and in about 70% of the games it was below it's starting point.Games numbers are relatively small for each team,so conclusions are necessarily tentative.Liverpool appear to be the most bad tempered of the original big four,5 of their 6 red card games came when the Reds were performing worse than expected.Chelsea were the team who appeared least concerned with the current match position before they saw red.

The figures appear to confirm that teams who are playing badly by their expected standards are likely to compound the problem by having players dismissed.The question now becomes is the effect universal or is it more pronounced when those struggling to perform are the best teams in the division,after all they have more to lose than teams with lower pre match expectations and their under performance will be self-evident to their players.The average fall in EP at the time of the dismissal is around 20%,so in the next part of this series I'll take a representative sample of games not involving the big four and see if the red card situations remain the same.

EPL Decision of the Week.Rodwell's Red Card.

No doubt where the decision of the day was made in the latest round of Premiership games.The Merseyside derby was shaping up to be a tight and closely fought affair until Martin Atkinson surprised everyone by red carding Everton's Jack Rodwell for a tackle that barely merited a free kick.The ref was perhaps poorly positioned,too close to the incident and Rodwell's initial movement towards the ball was with his studs momentarily raised.But the tackle was both clean and not made with excessive force,so the decision to rescind the dismissal came as no surprise.

But what in actual hard points did the incorrect verdict cost the Toffees.Liverpool were marginal favourites at the kickoff despite being the visiting side.Ground advantage tends to be less significant in local derbies and on current form the reds are clearly a slightly superior side to their near neighbours.

Liverpool would expect to average about 1.3 goals and allow 1.2 goals in such circumstances and after 22 minutes,just prior to the red card these numbers had decayed to about 1.04 and 0.96 goals respectively.At
0-0,those figures translate to about 1.28 league points on average for Everton and they would go on to win a goalless game,22 minutes old about 33 times out of 100 and draw about 30 times.

The red card changed all of that.

Everton's expected points fell from 1.28 to 0.48 upon the dismissal and their chances of winning the game fell from 33 in 100 to just 8.A draw still remained a reasonably likely scenario at 23 times per 100.Everton would have been in a marginally better position if Liverpool had scored and Rodwell had not been dismissed.

As red cards go it had a major impact on the game,even more so for it being subsequently rescinded.

By the time of the next major,but this time non controversial decision in the 44th minute,Everton had clawed their Expected Points total back to just over half a league point.In awarding the visitor's a penalty,Atkinson caused Everton's EP to plummet to a shade over 0.2,but Howard's save restored it to near to pre penalty levels.

Events.
0-0,Rodwell Red Card,23'
0-0,Penalty awarded to Liverpool,44'
0-0,Kuyt misses Penalty,44'

Individual Player Winning Contribution for Stoke 1 - 0 Liverpool.

Success Probability (SP) is the probability that a team will win a game plus half the probability that a team will draw a game from any chosen point in the game.

1-0,Walters (pen),21 mins.


Subs.
Wilkinson on for Huth,64 mins.
Jones on for Etherington,68 mins.
Palacios on for Delap,71 mins.


Bellamy on for Henderson,67 mins.
Carroll on for Kuyt,68 mins.
Johnson on for Skrtel,81 mins. 

Only one story here.Liverpool's pre game success probability had fallen from 0.571 to 0.564,before Carragher's unnecessary foul single handedly sent it plummeting to 0.36.Penalties are converted at around 70+% so it was odds on that the penalty would be converted and their SP would fall even further to 0.293.Only a Reina save or Walters miss would restore Liverpool's SP to it's pre penalty levels.

The foul was entirely down to Carragher,so he's penalised for the entire fall immediately after the penalty award.If Reina had made the save he would have been credited with restoring Liverpool to the pre award state.However,Walters converted,but Reina at least had the small consolation of only being penalised 20% of of the move from the SP immediately following the award and the SP following Walters' goal.A large amount of the negative SP from a penalty is borne by the player who commits the infringement.The rest of the back four were penalised 44% of the shift in SP after the score for allowing the situation to develop initially and so Carragher received a double whammy of negative SP.Short of being sent off as well,which he arguably should have been,it's hard to imagine how a defender could have a more damaging 60 seconds of play.

Walters both scored and created the goal by being the fouled player,so he gets the full 100% credit for the winning goal.

 Stoke.

Player.	Win Contribution.
Begovic.	0.066
Huth.	0.049
Shawcross.	0.066
Upson.	0.066
Wilson.	0.066
Delap.	0.051
Whitehead.	0.066
Pennant.	0.066
Etherington.	0.050
Crouch.	0.066
WALTERS.	0.337
subs.
Wilkinson.	0.017
Jones.	0.016
Palacios.	0.015
Total	1.000

Liverpool.

Player.	Win Contribution.
Reina.	0.013
Agger.	0.017
CARRAGHER.	-0.187
Enrique.	0.017
Skrtel.	0.028
Adam.	0.020
Downing.	0.020
Henderson.	0.036
Lucas.	0.020
Kuyt.	0.038
Suarez.	0.022
subs.
Johnson.	-0.011
Bellamy.	-0.016
Carroll.	-0.016
Total.	0.000