There is probably a slight effect, but the fact that when you analyze the data there's almost no strand of validity to the argument that certain catchers get more out of their pitchers than other catchers. Like I said, there is probably an effect, but the magnitude of this effect is worthless. I do agree that giving a catcher an off day one time through the rotation is a good idea, especially during the summer when the Cubs play a lot of day games. Zambranos our best bat from the mound so it makes sense to have a personal catcher for him, even more so when factoring in the recent altercations between Z and Barrett. But still, MB's lack of success with Big Z this season is pretty meaningless IMO. While this more of a negative towards Z than Barrett in this example, but Zambrano's fragile state of mind isn't helped by a catcher with an unusually high # of defensive lapses so far this year. While I'm not a big fan of trying to conclude anything from CERA & it doesn't need to be applied here to add validity to keeping Barrett from catching Zambrano, it just makes sense to keep Blanco (who is more take charge) with someone like Zambrano every 5th day.