I see, thanks.
I'm not sure I agree entirely with you about the second chart solely favoring players with few minutes though. I see what you're saying and all, but if you want to go into details like that, I'm sure one could make the counter argument, that those players doesn't get any real match rythm, thus being at a disadvantage compared to the players who get 90 mins regularly.
I've followed statistical analysis in football for some time now, especially productiveness and effectiveness, and I think there is clear correlation between, more you play, on average less effective you are.
Lets look at this way, player A plays two games, being best in one game and fourth in second. Player B plays the second game being the best. With that the first one would suggest them being equal and the second chart would suggest that the player B would have been better, when actually player A gave more overall quality.
But you are correct it isn't that simple as I put it worth, and that's why I said: tries to take that anomaly out. And like I said, it's just a suggestion.