I'll add something to what Chorizo said. From my past pitching experience, a lot of it has to do with (as Sheets put it), "being on the same page." Back in my glory days, the catcher with whom I played the most knew exactly how I pitched. He knew what my strengths were, he knew what my weaknesses were. He knew how my pitches moved (ex: I am a lefty - my fastball naturally cut in on righties, my curveball was a Zito-esque 12 o'clock-6 o'clock breaker) and thus, where they'd end up based on where I started them. He knew how I liked to throw. I did shake him off at times, but we were almost always on the same page - it gave me confidence that I could pitch my game and not worry about what he was doing. Example of when my catcher called a pitch that I would not have normally chosen, but was exactly correct: Early in a game my senior year in high school, there were two guys on, two out. The opponent's masher was up. I never gave up a home run, but I almost did during this at-bat, and was lucky the wind blew it foul. We were at a full count. I just assumed that I was going to see the catcher drop one finger down, but to my surprise, he called for the curve ball. Now, I had a nasty, nasty curve ball (oh, those were the days), and while I had very good control, I almost never threw it with three balls. But when I saw the sign for the curve I sort of thought, "Hmm, what the heck. Let's go for it." So, I through a perfect curve that started outside and broke right over the plate, freezing the batter. The ump didn't expect it either, as he actually hesitated before calling it strike three. I know that was just one pitch of thousands, but I've always remembered it because of how impressed I was with my catcher's head for the game. He knew what I could do, he knew what pitch would be best in a situation, and he trusted that I could throw it. At the same time, I had confidence in his decision making, so I could concentrate on throwing pitches. On the other hand, once in a while, I would have to pitch to one of two other catchers, and it was awful. I still did fine, as I was a good pitcher, but I constantly wondered what the guys were doing behind the plate. They were basically just glorified backstops. I felt like, other than catching my pitches, that I had to do both of our jobs.