Well, they'd be throwing the superior member of that group of 3 going forward. The other two won't throw another pitch in the bigs this year. So, with their offense, it's no stretch. In fact, with a rotation of Wang, Mussina, Pettitte, Igawa, and Hughes, they'll go on some good tears when the bats are clicking.
As to the numbers, we'll just have to disagree. I think psychology certainly has more than a 5% impact during a streak of games, which typically last less than 2 weeks. If we were talking about the whole season, then I'd agree it's less than 5%. But, in a short window, the head can play bigger role.