I think players, GMs, and other baseball people acknowledge that certain players can't take the heat of the bright lights in NY and Boston. This is similar to pitchers that can pitch in the 7th or 8th but can't close out a game. The 9th is only 3 outs, but they are the hardest 3 outs for any pitcher. Is it because the batters are better in the 9th? No. The ballparks don't shrink in the 9th, nor does the strike zone. They are the toughest three outs because of the pressure, and many successful pitchers have been unable to succeed in that role.