I have my doubts as to the level of havoc it causes being anything but minimal, but MLB pitchers have commented on the fact that they sometimes pitch differently or pay too much attention to the runner. The fact that I love my wife and child is no less true because I can't show proof that I do. In Pierre's case, we have the benefit of him and Castillo batting almost exclusively 1 and 2 for several years. Look at the numbers, when Pierre is performing well(i.e. he's on base a lot), Castillo does poorly. When Pierre isn't performing well and not on base very much, Castillo performed very very well. Their OPS's made almost a perfect ratio. Not that I doubt you, but is there any sort of study or any numbers someone has crunced that support this conclusion? I'm curious as to how this conclusion was derived, as I'd never heard this theory before. Not a study by any means, but when Pierre was brought up at some point I looked up his numbers. We have the good fortune of Pierre/Castillo being 1/2 for a significant sample, and those were the findings. I have class to go to in a minute so I don't have time to look them up again, but someone feel free to look at their numbers. IIRC, the numbers held true for "runners on" situations as well as overall production.