The big points that I think win the fight for either Klitschko brother are as follows:
1. Experience - both brothers have been in big heavyweight title fights before, they've been in trouble, they've overcome trouble, they know what to expect and they don't get thrown by any variables that can occur in these big fights like fouls or cuts or knockdowns.

2. Accuracy - The bothers are economical in their offense, every punch they throw matters whether it hits the guard to draw attention or lands flush on the jaw they make their punches count and they are precise in their attack. I can't count the number of times I've seen Wlad land a jab and then land a right cross right behind it on the exact same spot and it's so quick that you can't adjust to block or avoid that.

3. Fundamentals - Both brothers (Wladimir more so) are fundamentally sound they throw straight punches, they use solid defense, they protect themselves, they have a set game plan and they follow it, they don't force the KO, they allow the KO to come to them.

All those along with height, weight, reach, power, etc. I just don't forsee the WBA title holder giving Wlad or Vitali much trouble. Sure the guy is fast, sure he has some pop, but he keeps the front hand down, he leaps in (bad news vs Wlad) throws 1 big punch at a time, and just the simple fact that the guy has NEVER EVER EVER EVER been in the ring with anyone remotely as good as either Klitschko brother will show during their fight should it happen. You look at Barrett, Valuev, Ruiz, and Harrison and tell me any of those guys are as fast as powerful or are even in their prime like the Klitschko's are.