The catcher may call the pitches (and he doesn't with all pitchers, there are plenty of veteran pitchers that call their own games, Verlander for example), but he is simply doing the catching. He isn't the one actually throwing the pitches, and facing the hitter. He doesn't impact K's and BB's enough. We know this after 100+ years of data and the realization that catcher don't impact many things, like K/BB etc. They just don't. They are crazy important, moral leaders, and are crucial consistently in a number of situations (can I throw this breaking ball with confidence with two outs and a runner on third?). But in terms of the pitcher actually executing his pitches, no. That's up to the pitcher himself.