Wednesday 1 August 2012

Direct Free Kicks. Always Take Your Best Shot.

The ball was carefully placed just right of the centre of the pitch and almost 38 yards from goal. An apprehensive wall was assembled 10 yards outside of the penalty area and Barthez barked out his instructions as Roberto Carlos prepared his run up that had stretched to beyond the arc of the centre circle. Seconds later the most iconic free kick of all time had been scored in an inconsequential friendly tournament in France. Ferociously struck with the outside of his left boot, the ball swerved from a trajectory 5 yards wide of Barthez's left hand post, dipped, before slamming against the inside of the upright and burying itself in the net.

A brilliant, majestic free kick that is unlikely to be repeated, certainly Roberto Carlos never came close to emulating his own feat, often struggling to even trouble the keeper despite constant repeated efforts. And there lies the paradox surrounding direct free kicks, as Roberto Carlos demonstrated in Le Tournoi and subsequently, they provide unforgettable moments, but they much more frequently fail to produce goals.

Goal attempts from direct free kicks are relatively rare beasts. The permanent members of the EPL since 2008-09 have averaged just under 20 such events per season and those teams average just over a goal and a half a season from direct free kicks. Below I've listed the each team's scoring record in such situations since 2008, the raw figures are taken from the EPLIndex website.

Conversion Rates For Direct Free Kicks For EPL Teams, 2008-2012.

Team. Direct Free
Goals Scored
from Kick.
Rate %.
Rate %.
Arsenal. 86 5 5.8 7.2
Aston Villa. 66 4 6.0 7.3
Blackburn. 76 5 6.6 7.4
Bolton. 84 6 7.1 7.6
Chelsea. 130 7 5.4 6.8
Everton. 71 9 12.7 9.1
Fulham. 69 6 8.7 8.0
Hull. 46 5 10.9 8.4
Liverpool. 67 5 7.5 7.7
Man City. 70 8 11.4 8.8
Man Utd. 91 10 11.0 8.8
Newcastle. 56 3 5.4 7.2
Stoke. 44 2 4.5 7.2
Sunderland. 61 8 13.1 9.1
Tottenham. 88 3 3.4 6.4
WBA. 49 6 12.2 8.7
WHU. 63 2 3.2 6.6
Wigan. 92 10 10.9 8.8
Wolves. 39 1 2.6 6.9

Before we can begin to quantify the value of direct free kicks, we need to take each team's actual performance record and use it to estimate the spread of talent with the group. Wolves have the lowest conversion rate at 2.6% and Sunderland the highest at 13.1%, but these percentages could fluctuate wildly with the addition or subtraction of one or two goals, such is the paucity of scores from relatively few attempts. The average conversion rate for all teams is just under 8% and such is the spread of conversion rates for all teams we can conclude scoring from a direct free kick is a talent, but the spread of talent is quite narrow. It's likely that the teams who have played in the EPL since 2008 would need to take upwards of 200 direct free kicks before we can begin see a separation of talent with the best having highest actual conversion rates. That's around ten seasons worth of shots.


Therefore we should be very wary about taking any of the conversion rates posted by teams at face value, even over four seasons the actual results posted by each team will be very heavily influenced by random chance. Roberto Carlos was obviously an extremely talented striker of a football, but the combination of biomechanics needed while completing the shot, the alignment of the defensive wall, the angle at which the ball struck the post and Barthez's (non) reaction time are each variables that can align or combine to produce a goal or just a marvelous failure. His Le Tournoi goal was certainly the product of skill, but randomness also played a significant role in that one attempt.

We must accept that even four years of direct free kick trials will be predominately the product of luck and will not come near to representing the true qualities of each team. Sunderland are way ahead of Wolves in recorded performance, but the true gap between their respective shooting abilities will certainly be much narrower. To get our best estimate of each side's true ability we need to add a large amount of league average conversion rates to each side's actual records.

I've done this in the final column of the table and my best estimate of the true conversion rates for EPL sides is much tighter than the actual record each has shown over the last four years. The worst sides are likely to convert direct kicks at around 7%, while the best are only a few ticks higher at 9%. We can now use these more representative figures to continue to evaluate direct free kicks.

Average conversion rates for all shots attempted in open play are well into double figures, so direct free kicks are inferior by comparison. However, once we start to compare open play shots taken from similar distance to typical direct free kicks, the picture changes. Direct free kicks must be taken from at least 18 yards from the goal line and on average they appear to originate from well into the mid twenties. Open play shots from similar areas of the field are only converted around 4% of the time. So even the poorest of EPL free kick takers will outshoot an average open play attempt from the same position. It appears that allowing a player to compose himself and a team to present their best striker of a ball as the taker more than compensates for the presence of a defensive wall.

For a team to profitably spurn the opportunity to shoot directly from a free kick they must instead be able to manufacture an open play attempt with similar chances of success. Shots taken in an arc approximately 16 yards from goal during open play have predicted conversion rates of around 7%, so a team will have to be capable of creating such a chance on average from every direct free kick they spurn to gain comparable value. In reality this won't be possible, nor would the chance be equivalent to a normal open play shot because the penalty area will be much more populated with defensive players.

Direct free kicks may be rare events where goals are infrequently scored, but given the choices, a shot is always the best course of action.

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