What I like about Fesenko is that he plays defense, he brings attitude, and doesn't replicate any of the players we already have. Young and big don't hurt, but I like him
I think Stiemsma is a bit overrated at the moment. Great energy, but only one above average skill that I can see (shot blocking). He's a pretty average rebounder for a big guy (about the same rate as JO), his jumper "looks" ok but the guy is shooting 42% and not scoring many points. He has no post defense and lousy help defense as well, outside of going for shot blocks. In short, a situational guy who does some things badly, some ok, and one thing well.
What I think is really going to be tested here is how Doc can manage the big guys. Playing Stiemsma vs Fesenko (assuming we get him) at the right times, KG at the 5, even going small (Rondo / Allen / Pietrus / Pierce / Bass) could play a big part in our success (or demise).
At least Fesenko has upside... I like him WAYYY better than someone like Ryan Hollins who's ONLY skill is being 7 foot and athletic.