My last
post asked the question whether many creative players, specifically Ozil and
Mata, were overrated because the basic metric used to rate them (key passes)
doesn’t take into account turnovers. We would really need to look at something
like the assist/turnover ratio in basketball to appreciate the full value of a
player’s creativity. I concluded that since we don’t currently have accurate
data, it is really hard to tell whether Mata and Ozil are overrated. But today,
I’m going to take a stab at it, using a relatively simple formula as a proxy.
The
assist/turnover ratio is brilliant in that you are comparing the number of
positive creative events (assists) a player has with the number of negative
creative events (turnovers) he has. To develop a proxy, we need to come up with
a positive event and negative event that we can easily measure. In coming up
with this formula, I stuck with the idea that the key pass should be the
positive event we look at rather than an assist. Since scoring is much more infrequent
in football, using key passes gives us more data and lets us focus on the value
the passer adds (rather than the shooter). For the negative event, I looked at
the total number of unsuccessful passes a player has (that is, (1-Passing
Percentage) * Total Passes). This formula allows us to look at the key passes
versus unsuccessful passes, and gives us a better idea of who the creative
players truly are.
There
are some obvious flaws in this. Many of a player’s turnovers are not the result
of a misplaced pass, but rather by being caught in possession of the ball, or
stopped when attempting to dribble around a defender. The key pass metric
itself is not perfect, and counts passes leading to a shot on target and of
target equally (at least Squawka, my data source for this project, does). Still,
there are some key advantages to using this metric when comparing players. It’s
not a counting stat, where the more you play the better you do, so there’s no
need to adjust for playing time. Unlike passing percentage, it doesn’t inflate
totals due to making more simple, short passes. And most importantly, it has
some way to measure mistakes and hold them against the player who makes them.
Using the proxy, I looked at all midfielders
with more than 20 key passes on the season. The leaders of the Key Pass list
contain some familiar names, along with a couple odd ones: Eden Hazard, Ozil, and
David Silva are examples of the former, Moussa Sissoko and Robert Snodgrass the
latter. How do they stack up in this new metric? See for yourself (data through 2/1/14).
| Assist/Turnover Ratio Proxy (key passes/unsuccessful passes) | ||||
| Player | Team | Key Passes | Unsuccessful Passes | A/T |
| Mirallas | Everton | 42 | 85 | 0.49 |
| Mata | Man United | 32 | 71 | 0.45 |
| Nasri | Man City | 43 | 97 | 0.44 |
| Townsend | Tottenham | 21 | 55 | 0.38 |
| Silva | Man City | 45 | 118 | 0.38 |
| Willian | Chelsea | 27 | 72 | 0.38 |
| Jarvis | West Ham | 22 | 60 | 0.37 |
| Navas | Man City | 35 | 96 | 0.36 |
| Downing | West Ham | 32 | 90 | 0.36 |
| Lennon | Tottenham | 23 | 67 | 0.34 |
| Snodgrass | Norwich | 46 | 138 | 0.33 |
| Ward-Prowse | Southampton | 29 | 88 | 0.33 |
| Hazard | Chelsea | 55 | 169 | 0.33 |
| Ozil | Arsenal | 44 | 140 | 0.31 |
| Sessegnon | West Brom | 23 | 74 | 0.31 |
| Sterling | Liverpool | 24 | 79 | 0.30 |
| Ben Arfa | Newcastle | 20 | 66 | 0.30 |
| Dembele | Tottenham | 25 | 83 | 0.30 |
| Sissoko | Newcastle | 49 | 169 | 0.29 |
| Amalfitano | West Brom | 31 | 107 | 0.29 |
| Giaccherini | Sunderland | 22 | 77 | 0.29 |
| Ki Sung-Young | Sunderland | 22 | 81 | 0.27 |
| Johnson | Sunderland | 29 | 107 | 0.27 |
| Holtby | Tottenham | 20 | 81 | 0.25 |
| Eriksen | Tottenham | 26 | 110 | 0.24 |
| Redmond | Norwich | 22 | 94 | 0.23 |
| Westwood | Aston Villa | 34 | 147 | 0.23 |
| Henderson | Liverpool | 37 | 164 | 0.23 |
| De Guzman | Swansea | 30 | 133 | 0.23 |
| Gouffran | Newcastle | 20 | 90 | 0.22 |
| Larsson | Sunderland | 26 | 119 | 0.22 |
| Puncheon | Crystal Palace | 29 | 133 | 0.22 |
| Bannan | Crystal Palace | 20 | 92 | 0.22 |
| Gerrard | Liverpool | 35 | 162 | 0.22 |
| Whittingham | Cardiff | 36 | 170 | 0.21 |
| Cazorla | Arsenal | 29 | 142 | 0.20 |
| Lallana | Southampton | 30 | 148 | 0.20 |
| Oscar | Chelsea | 27 | 134 | 0.20 |
| Cabaye | Newcastle | 31 | 156 | 0.20 |
| Davis | Southampton | 28 | 143 | 0.20 |
| Wilshere | Arsenal | 25 | 130 | 0.19 |
| Noble | West Ham | 38 | 201 | 0.19 |
| Pienaar | Everton | 26 | 139 | 0.19 |
| McCarthy | Everton | 24 | 134 | 0.18 |
| Routledge | Swansea | 22 | 124 | 0.18 |
| Coutinho | Liverpool | 29 | 164 | 0.18 |
| Adam | Stoke | 26 | 152 | 0.17 |
| Brunt | West Brom | 23 | 136 | 0.17 |
| Barkley | Everton | 21 | 126 | 0.17 |
| Lampard | Chelsea | 21 | 128 | 0.16 |
| Fernandinho | Man City | 22 | 142 | 0.15 |
| Huddlestone | Hull | 37 | 239 | 0.15 |
| Fer | Norwich | 21 | 149 | 0.14 |
| Ramires | Chelsea | 25 | 178 | 0.14 |
| Shelvey | Swansea | 26 | 186 | 0.14 |
| Livermore | Hull | 22 | 175 | 0.13 |
| Barry | Everton | 22 | 190 | 0.12 |
| Ramsey | Arsenal | 20 | 198 | 0.10 |
| Jedinak | Crystal Palace | 21 | 278 | 0.08 |
Observations:
1.
Mirallas tops the leaderboard! Didn’t see that
coming, but he has been having a great year. On the other hand, Ross Barkley is
near the bottom. Barkley has been getting a lot of praise, but I think this
adds to the evidence that he’s experiencing the “British media fawning over an average
young British player” phenomenon.
2.
Note that true central midfielders tend to
perform a lot worse by this metric, as you’d probably expect. Lampard,
Fernandinho, Barry, Fer, Huddlestone, and Adam all have a reputation as good
passers, but their central position does mean they pass the ball more often,
and thus misplace more passes. This may also be because wingers/attacking mids
are more prone to losing the ball in possession, something not taken into
account in this metric.
3.
Team shot preferences do play a role here. For
example, Spurs players will probably be overrated since they take so many shots
form distance, a shot which usually doesn’t require as incisive a pass. This
could be fixed by having key passes defined as passes leading to a shot on
target, something that is much harder to do from distance. West Ham are another team whose players might be similarly affected.
4.
Two that did better than I expected: Juan Mata
and Willian. Hazard is the name people talk about in the Chelsea attack, but
for all his speed his passing leaves a lot to be desired. Willian has both
attributes, and is a relatively unsung player at this point in time. I thought
Mata might drop a bit by this metric, but he did quite well. If you give him a
free role, he can be very dangerous. Hopefully United will screw him up like
Kagawa and Anderson.
5.
Aaron Ramsey is an odd case. Second from the
bottom on this list, but he has six assists. His teammate, Mesut Ozil, does
well in this metric but not spectacular. I think this provides a more
appropriate reflection of his season.
