1. lack of consistency
2. lack of optimal movement
3. lack of a more dominating serve
he can compensate for some of his deficiencies if he can develop a far more dominating serve. that goes a long way.
top players move better and they are simply more consistent. he is also terrified of the net. no harm in going forward and giving them different looks. you should be able to go in when you get or create those opportunities.
This is a very good point. I've often noticed during Berdych matches that he gets a ton of easy put away volleys which he fails to jump on by staying back. He'd make his life a lot easier if he could move in at the right times and finish points quicker. He's not the only modern player with a big game who doesn't do this though. He's just not used to volleying.