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Sunday 25 March 2012

Liverpool's Failing Attack.

It should have been a perfect match.John W Henry's purchase of Liverpool football club could have led to the implementation of the kind of under valued asset buying that under pins the Moneyball concept.The Fenway Sports Group already owned the baseball franchise in Boston and had a direct line to the Brains Trust who had devised the Moneyball concept when they bought out the previous American owners of Liverpool,Hicks and Gillett.Within months they had removed the underperforming manager and installed Dalglish as first caretaker and then as the permanent boss.They also bought with them a war chest of cash that eclipsed all but the Premiership's massive spenders.

Dalglish for his part had assembled an expensive,but not excessively so Premiership winning team when unfashionable Blackburn Rovers had pipped Manchester United on the last day of the 1994/95 season.Rovers were built on an impressive goalscoring record,mainly provided by the twin striking force of Shearer and Sutton and a good but not great defence that allowed just under a goal a game.Dalglish of course was a striker in his playing days,so it was to be expected that he would pursue the attacking route that had served him well seventeen seasons previously at Blackburn.Of the £100+ million that he spent during the early months of his tenure,the vast majority of the cash was splashed on attacking and midfield options.The hoped for twin striking threat of Suarez and Carroll alone accounted for £60 million,Downing,paraded as a potential "Moneyball" buy came at the cost of £20 million and Adam,Henderson and Coates amounted to a further £30 million.

If we look at the goal scoring records of all teams sorted by finishing position,we see that better teams on average do score more goals per game than do poorer ones.It's a long,long time since Manchester City simultaneously topped the premier division's scoring charts and also found themselves relegated to the second tier.Nowadays,every top three finishing side since 1998 had amassed at least 1.5 goals a game.A fourth place shot a Champions League qualification was more forgiving of a team's attacking intent,with a third of such teams scoring less than 1.5 goals per game.So the idea that goals boost finishing position appears sound in theory.In practice the expensive implementation at Liverpool under Henry and Dalglish proved to be a massive disappointment.Liverpool's current 1.27 goals per game was the average return for a team finishing just inside the top ten and only Everton in 2004 managed a 4th place finish while being so lacking in front of goal.






Goals allowed show a similar expected trend when plotted against finishing position.The less goals per game you allow the higher up the table you tend to finish.The majority of top four finishers allow less than a goal a game,a couple even manage to breach the 0.5 goal per game barrier and none over the period got close to allowing more than a goal and a half a match.In this respect Liverpool can claim to have possessed a typical top four defence.Their record of allowing exactly one goal a game sits very well with the average record of third and fourth place finishers,a realistic target for a well resourced team who have decided to avoid getting into a chequebook duel with the league's three mega spenders.It also tallies quite well with their defensive record over the previous couple of years,indicating that a richness of defensive talent was already at the club.







We can now put the scoring and conceding requirements together in a plot of a team's goal difference and finishing spot.A goal difference of 0.75 or better has virtually guaranteed a top four finish,so Liverpool's current +0.2 goals per game is entirely consistent with their current lowly position.And it reiterates where the current underperformance lies.Even if the Reds defence performed at historically exceptional levels,the poor returns from the strikers would make a top for finish highly unlikely.A cursory examination of the causes of Liverpool's failure to threaten a Champions League spot lies squarely at the feet of that part of the team that has had almost all the money thrown at it.A most un Moneyball outcome.





























Having identified the problem,we can move on to see what kind of return Liverpool have enjoyed for their initial investment and we will start with the attacking side of the ball.I'll again use the concept of Expected Points to "value" each goal scored by the team upto and including their embarrassing defeat at QPR.EP is derived from the probability that a team will win or draw against their current opponents given the current score and time remaining and the change in EP from the moment just prior to the goal being scored and immediately after can be used to evaluate the worth of that goal.

The value of a goal is very context dependent.First goals consistently move a team's EP by reasonable amounts,whereas last minute strikes have much greater variation,either counting for very little in lopsided games or a great deal if the prior game state is close.

How Liverpool's Goalscorers Increased their Team's Expected Points.

Opponent.
1st Scorer
Min.
EPPre Goal.
EPPost Goal.
2nd Scorer.
Time.
EPPre
Goal.
EPPost
Goal.
3rd Scorer.
Time.
EPPre Goal.
EPPost
Goal.
Sunderland
Suarez,12
2.12
2.67
@Arsenal.
Ramsey(og)78
1.56
2.82
Suarez,90
2.91
3.00
Bolton
H'derson,15
2.26
2.75
Skrtel,52
2.76
2.96
Adam,53
2.96
3.00
@Stoke
@Spurs
Wolves
Johnson(og)11
2.35
2.80
Suarez,38
2.78
2.96
@Everton
Carroll,71
1.84
2.88
Suarez,82
2.91
3.00
ManU
Gerrard, 68
1.13
2.60
Norwich
Bellamy, 45
2.16
2.80
@WBA
Adam(p), 9
1.77
2.45
Carroll,45
2.51
2.82
Swansea
@Chelsea
Rodriguez,33
0.987
1.88
Johnson,87
1.03
2.65
ManC
Lescott(og),33
0.554
1.32
@Fulham
QPR
Suarez,47
2.14
2.79
@AVilla
Bellamy,11
1.82
2.50
Skrtel,15
2.50
2.85
@Wigan
Blackburn
Rodriguez,53
1.17
2.15
Newcastle
Bellamy,29
1.20
2.03
Bellamy,67
1.71
2.71
Gerrard,78
2.76
2.98
@ManC
Stoke
@Bolton
Bellamy, 37
0.43
1.04
@Wolves
Carroll,52
1.75
2.65
Bellamy,61
2.68
2.95
Kuyt,78
2.98
3.00
Spurs
@ManU
Suarez,80
0.016
0.17
Arsenal
K'cielnly,(og)23
1.71
2.46
@S'land
Everton
Gerrard, 34
1.83
2.57
Gerrard,51
2.60
2.92
Gerrard,90
3.00
3.00
@QPR
Coates,54
1.71
2.61
Kuyt,72
2.68
2.96

The change in EP post and pre a goal does a neat job of quantifying the value of each goal and a cumulative running EP total can also illustrate the player's goalscoring contribution over a season converted to a points expectation.However,frequency of opportunity isn't accounted for,so below I've included figures for goals scored and total EP generated per minute of player playing time.The numbers have been multiplied by 1000 to reduce the amount of potentially confusing decimal place zeros.The ideal player and candidate for a team's end of season awards would be one who generated high proportions of both goals per minute and EPs per minute.In short,lots of goals when the team needed them most.

At this point the analysis becomes more subjective,but I've arranged Liverpool's scorers in descending order of combined attainment in each category.Craig Bellamy's goals were relatively frequent,for Liverpool at least and relatively important.He scored a couple of game opening goals and as Omar points out here in his 5 added Minutes Blog,opening goals are almost always significant strikes and he scored important goals against Newcastle and sealed victory at Wolves.Rodriguez didn't score frequently enough to topple Liverpool's free transfer and Gerrard's higher strike rate was dilute by his insistence in claiming a hat trick in the derby game.

It's only when we reach midtable that the big money men begin to appear.Suarez,like Bellamy opened the game's scoring twice,but he also claimed three low value closing goals,while Carroll was generally unproductive.Downing has yet to score outside of the Cup runs and Henderson hasn't scored since the opening phase of the campaign.

It's probably worth pointing out that these numbers are primarily descriptive as opposed to predictive,the sample sizes are too small in any case.They indicate how the points were won,but can't claim to predict how they will continue to be won.However,much in football revolves around how players and managers are perceived by employers and fans and the longer a big money star appears to under perform,then the shorter the leash becomes.Henry apparently envisaged an initially large outlay would be followed by a self sustaining period where Champions League money would flow into the club and that won't happen next year.

Summary of the Worth of Each Goal Scored by Liverpool Players in 2011/12 so far.

Player. No. of  Goals. Total EP. EP per Goal. EP per Minute.
(x 1000)
Goals per Minute
(x 1000)
C Bellamy 6 4.01 0.67 4.44 6.63
M Rodriguez 2 1.87 0.94 4.67 4.99
S Gerrard 5 2.75 0.55 3.21 5.83
S Coates 1 0.90 0.90 3.00 3.34
A Carroll 3 2.32 0.77 1.58 2.05
L Suarez 6 1.72 0.29 0.89 3.10
Own Goals 4 3.23 0.81 1.18 1.46
G Johnson 1 1.62 1.62 1.05 0.65
C Adam 2 0.72 0.36 0.33 0.92
D Kuyt 2 0.30 0.15 0.18 1.22
M Skrtel 2 0.55 0.28 0.23 0.85
J Henderson 1 0.50 0.50 0.24 0.49

For completeness I've added the decline in Liverpool's in game Expected Points caused by the goals they conceded.A good team with a poor defence often presents it's strikers with the opportunity to score high value goals by keeping the games close.If the situation is reversed and a poor attack fails to put distance between their team and their opponents,the defence can find itself conceding numerous high cost goals and that appears to have occured in the case of Liverpool.Although they allowed few goals,they were invariably first game goals or late winners and the increasing number of second and third goals that are now being scored implies that the effort may be taking it's toll.

How Goals Conceded by Liverpool Decreased their Expected Points. 

Opponent. 1st Scorer.
Min.
EP Pre Goal. EP
Post Goal.
2nd Scorer.
Time.
EP Pre
Goal.
EP Post
Goal.
3rd Scorer.
Time
EP Pre Goal. EP Post
Goal.
Sunderland Larsson,57 2.70 1.81
@Arsenal.
Bolton Klasnic,90 3.00 3.00
@Stoke Walters(p),21 1.54 0.76
@Spurs* Modric,7 1.36 0.66 Defoe,66 0.10 0.01 Adebayor,68,90 0.00 0.00
Wolves Fletcher,49 2.97 2.78
@Everton
ManU Hernandez,81 2.60 1.16
Norwich Holt,60 2.81 2.03
@WBA
Swansea
@Chelsea Sturridge,55 1.71 0.95
ManC Kompany,31 1.29 0.63
@Fulham Dempsey,850.97 0.10
QPR
@AVilla
@Wigan
Blackburn Adam(og),452.26 1.37
Newcastle Agger(og),25 2.06 1.20
@ManC Aguero,10 0.99 0.39 YaYa,33 0.35 0.09 Milner,75 0.08 0.01
Stoke
@Bolton Davies,3 2.07 1.33 RCoker,29 1.12 0.50 Steinsson,50 0.89 0.32
@Wolves
Spurs
@ManU Rooney,47 0.97 0.298 Rooney,50 0.29 0.06
Arsenal vanPersie,31 2.47 1.66 vanPersie,91 1.13 0.11
@S'land Bentdner,56 1.54 0.60
Everton
@QPR Derry,77 2.98 2.74 Cisse,86 2.83 1.30 Mackie,91 1.15 0.12

*Adebayor's 2 goals have been compressed into one column.By the time they arrived Liverpool were 2 goals down and a similar number of players down on the pitch as a result of red cards.

In the next part,we'll look at the kind of statistics that might have encouraged the Liverpool Group to invest substantial sums on the players they did,how predictive and sustainable between seasons those stats are and how successful were their in game substitutions.

For a fascinating look at how the Red's season has been affected by penalty kicks check out Omar again here.

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