Eurosport.com
The Player Performance Index (PPI) is a numerical and objective evaluation of the performance of a Player during a match.
The actions specific to each role are taken into consideration and for each kind of ball played, a rating is calculated on an historical base and on the expectation of the performance for a player in that role. To give an example, a goalkeeper should save every shot he faces. Consequently, when he concedes a goal, it is considered a negative point in his evaluation, regardless of whether he was directly responsible for it or not. In the same way, if a team concedes a goal, it counts against all the defenders in that team. On the other hand, an interception or a tackle won counts as a positive factor. Obviously, a pass is not worthy of the same recognition as a goal, and is therefore not given the same rating, having its own 'coefficient of importance.'
The PPI is then calculated converting the evaluation obtained on a scale between zero and 10. An 'adequate' performance is represented by a value of 6, a very poor performance will result in a PPI of around 2, while a superb performance will result in a PPI between 9 and 10.
Warning: PPI will only rate players that have been on the pitch for more than 30 minutes
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edit1 Hm wait I might have made a mistake though, perhaps the rating i submitted is just for one day, I'll check it up.
edit2 Na it was correct. :O