Why Aren't Baseball Players Be Athletic?

[theBruiser500]

One of the reasons I don't like baseball is because they are so unimpressive to me as athletes, really it's frustrating to watch. So we have these baseball players here getting enormous amounts of money- I wonder how much they even practice. It doesn't look like a lot, why are some of them fat, why couldn't Manny make the simpliest of defensive plays in this game vs. the Yankees in extra innings when he turned that single into an out. Compared to other sports baseball players are like big ogres.

Some people have told me the players are fat because it adds power to their swing, but this seems like a cop out to me. Why can't they be not fat and strong? What's the deal guys?