Posted on Sunday, March 3, 2013 by everesty nuralia pritama
One of the areas we need to work on over the summer is how shots on target are converted into goals, specifically the split between types of shot. We've observed that, on average, shots on target become goals at a league wide steady rate (30%-33% depending on position), but on an individual level things are more complicated. We consistently see players like Adel Taarabt show up as outliers in that they've taken a lot of shots, hit the target but yet not received the final reward.
One of the obvious starting points is to look at the ratio of shots taken inside and outside the box, and this is something that is already baked into the current model. However, playing around with some data recently, I put together a graphic which hopefully lays out some of the questions that remain unanswered, and I hope to spark some debate to push this forward in the offseason.
SiB Ratio - percentage of shots taken inside the box
G/SoT - percentage of shots on target converted into goals (excluding penalties)
On first glance, the signs aren't too promising here. We don't observe a particularly strong relationship between the two ratios and we see successful players scattered all over the chart. If we focus on those players who've notched more goals this year (represented by a larger circle) though, we can see something develop, with only a handful of players managing to really defy the logical trend of having a lower G/SoT rate is they taken less shots inside the box:
One thing that could potentially explain some of this variance is the fact that this quartet of players all take a large number of set pieces, all ranking in the top 10 among midfielders:
1. Bale 24 attempts, 0 non penalty goals
4. Gerrard 18 attempts, 0 non penalty goals
7. Cazorla 16 attempts, 0 non penalty goals
10. Lampard 14 attempts, 1 non penalty goal
I must say it wasn't particularly intuitive to me to think that taking set pieces would be a bad thing for a player's stats, but it does seem that in terms of their impact on ratios, scoring a long range free kick does seem harder than scoring a long range effort in open play. I therefore think that for future iterations of the model we need to further distinguish between not just SiB and SoB but also shots taken from set pieces. The issue is that from the Opta data I currently use, we don't seem to have a distinction between shots from set pieces in terms of long range efforts and those where a player gets on the end of a cross from a set piece (which presumably have a decent chance of being converted). As I say, the search for a magic formula continues.
At this point in the season there are more pressing issues to think about (like trying to field a GW29 lineup!) but I want to keep these questions in the background to make sure they are ready to be discussed over the offseason. On that issue, I will be guest writing in a new fantasy publication called InsideFPL which launched last week. At this stage it is still a developing idea so any suggestions or comments would be welcome but I encourage everyone to sign up and give it a read as it could represent an exciting forum to discuss fantasy football and there are some excellent writers already on board.
Category Article English Premier League, Fantasy Sport, Football, Premier League Fantasy Football, premierleague.com
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