Shields, who tied a Major League record by surrendering six home runs, has boasted significantly different splits when pitching to Jaso and Tampa Bay's other two catchers, Kelly Shoppach and Dioner Navarro.
Through 65 1/3 innings with Jaso, Shields has posted a 6.75 ERA with an opponents' batting average of .314. In contrast, over a combined 81 1/3 frames between Navarro and Shoppach, Shields has an ERA of 3.32.
Despite being well aware of the drastic difference in splits, manager Joe Maddon does not want to outlaw the Jaso-Shields tandem just yet.
"I honestly don't think Jaso is a bad pitch caller," Maddon said. "I don't. I think he's got a pretty good feel for what's going on out there. And at the end of the day the pitcher is always responsible for calling the pitch that he wants to throw. That's one thing we've always talked about from Day 1. I've [seen] a lot of improvement with Jaso this year, and that was a pretty good hitting ballclub yesterday.
"I think Jerry Grote could have caught yesterday, Johnny Bench could have caught yesterday and Therman Munson could have caught yesterday."