Well, i wouldn't put it that way, the idea is to point those players who are under their performance expectancy, and debate about it with perspective and criteria.
I hate TF, but if you look at the standings, the team is 2 games behind NY, at this point, the team is leading the wild card column, 2/5 of his starters have been on the DL (now, 1 recently activated and the other with an eminent surgery, both with terrible numbers so far), several players like CC started just pathetic, so... i would weight the hurting in somebody else before TF, wouldn't you?
anyway... what would be the percentage in success/failure of a manager in a MLB team? 20%?