My beefs, in no real order:
Gives a lot of generic calls. For example he'll do stuff like "2-1 on the batter". Come on John, I know this is TV but just give us the names, your producer can whisper it in your ear. He also repeats phrases, and this is part of the generic feeling, almost like a video game announcer. Every time the last two nights the Cubs scored he used "and the Sox' lead is cut to ____". OK, that's fine, use that once, use it twice, but not every single time the Cubs score. How about you throw in a "And the Cubs score 2 to make it a one run ballgame".
Ballwashes the Sox and players. This one doesn't need much explanation we got the Iraqi defense minister in the booth.
Constantly is mentioning how it's his "first". All this does is remind us how he's not familiar with the Sox, isn't familiar with the opposition, isn't familiar with being a everyday MLB play by play guy in general.
Absolutely never mentions any advanced stats. I appreciated that Jason would sometimes attempt it.
All in all it adds up to a guy that is just a constant reminder of how excellence or even competence isn't required to work on the South Side.