Whatever device you're using for MLB.tv, you're lucky if you're not seeing their repetitive set of commercials during inning breaks -- I see them on both computers and when watching through my Apple TV.
I'm assuming you realize this, but for the benefit of other people reading the thread: you'd need MLB Extra Innings plus the Sports Pack in order to get the games and the pregame and postgame shows through DirecTV.
"Coming up on Rays Live, the postgame, brought to you by Checkers..."
I watch MLB-TV on my computer, Roku Box and my XBox 360, so I do see a difference between innings. I use the Roku box the most and it has very little commercials.
I have the Premier package so I get the pre and post game with DirecTV.