FenerbahÁe fan here, just a little bit info on Wanamaker:
Pros: He can do a little bit of everything, good finisher with contact under the rim, decent shooter, can drive & kick and find open man, very strong frame, can stay in front of all Euro guards, had a great year under the tutelage of the greatest Euro coach ever, doesn't crumble under the pressure and performs at big games
Cons: Not a great decision maker - he settled for too many mid-range shots although he can bulldoze his way to the rim in Europe, not great athletically at the NBA level, mediocre P&R vision (can't thread the needle to the roll man), he is very emotionless which can be a problem for a bench guy if you want energy from him
All in all, I believe he is a better player than Larkin without a doubt. The question is if he's the guy Stevens and Celtics needs. I'd be really sad to see him go as he always produced at Euroleague games, he contributes even when it's not his day.