We all have our favourite players. Those whose names we yearn to see whenever the onslaught of team news tweets emerge from journalists’ accounts 60 minutes prior to kick off.

And we’ll all have different reasons for holding them in such high regard. But whatever it is we enjoy about how they play the game, if we like them it’s for one general reason: the team plays better when they’re on the pitch.

Accurately quantifying that importance is somewhat harder though. A common sight on social media is the with/without win percentage stat.

Liverpool's win percentage with Jordan Henderson in the team: 61.5%

Liverpool's win percentage without Jordan Henderson in the team: 33.3% pic.twitter.com/zGNmK99X9S

— The Anfield Wrap (@TheAnfieldWrap) February 28, 2017

That’s a bit simplistic though. Liverpool’s first team have lost five matches this season, with Sadio Mané, Andy Robertson and Virgil van Dijk starting every game. Should they be dropped? Of course not. Football is too complex to assign a win or a loss to a single player; yes, even Adrián against Atletico Madrid.

We could look at goals scored and conceded while a player is on the pitch, but that’s still pretty basic, and leaves players at the mercy of finishing and defensive errors and so on. Quantifying a player’s contribution beyond the tried-and-trusted statistics is arguably football’s latest arms race at the pinnacle of the sport. Dr. Ian Graham, Liverpool FC’s head of research, spoke about this in a must-read article with the New York Times. The piece gave an insight into the work he does, such as how he:

“spent months building a model that calculates the chance each team had of scoring a goal before any given action — a pass, a missed shot, a slide tackle — and then what chance it had immediately after that action. Using his model, he can quantify how much each player affected his team’s chance of winning during the game.”

Oh to be as smart as Dr. Graham. But while his work is beyond the ken of the vast majority of us, thanks to FBRef.com, and the Statsbomb data they share on their site, we can attempt a simplified version.

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