[nomo17k]

I rarely hit HRs with contact swing. It's useful for avoiding swing & miss, but you'll have a less chance on driving the ball. I only use it when I don't want to strike out or just want to put balls in play (e.g., hitting a grounder with a runner on third). You'll notice the exit speed with contact swing is generally slower even when you square up.

Power swing, you'll hit harder if you can make a solid contact, but your bat control suffers (i.e., you'll end up with more swing and misses). So I would only use it only when I'm looking for a specific pitch (both location and speed). The exit speed with power swing is generally much faster when you square up. In turn, if you hit a grounder with a man on first, you might get more GIDPs.

In MLB 13, power swing is pretty effective... too effective IMO. If you play at a lower difficulty where PCI is generally big, you can hit HRs all day long by just waiting on a mistake pitch down the middle...