Players these days miss out due to little injures as they know one knock on the leg could effect their game.
If say Nimely had a bad ankle and could only run 70% of his top speed, he may not be able to reach balls put through to him, meaning the fans will get on his back.
If a player is carrying a knock at the highest level it could effect their game play for themselves and others around.
Yes a do agree people paid that amount should put more effort in but as being a footballer at sunday league level myself, knowing I have a knock could effect massively for the team.