this can't be quoted enough, because this is so true, something I feel like people forget way too often.
not everything in baseball can be put into numbers to calculate.
you can't calculate what is going on the mind of pitcher 1, or pitcher 2, or pitcher 100, or pitcher 200.. all of which are different from each other. and they do effect how they perform.
player X might be tight, thinking too much, putting pressure on himself, and need to loosen up. he might go out that night and get laid, and then the next day is more lose and able to play differently.