If anyone is thinking Amir Johnson is another Ibaka they'll be disappointed. Amir is not an NBA center, he'll have trouble against powerful talented PF's, never mind 7' 280 lb. centers. Amir is not 6-10 or 6-11 and long. He's got good size for an NBA PF, and he works hard. His stats are not great or even real good.
The Celtics still need a front line center, Amir can play center in a small fast line up. But the Celtics still need a presence in the middle.
His advanced stats are fantastic. He's long been a darling of the analytics group. Counting stats aren't that great, but we didn't sign him to go 18/10 every night.
If your expecting Ibaka you'll definitely be disappointed, but why would anyone be expecting that? Johnson is a plus defender from both the 4 and 5 spots. It's long been said that he's certainly at least 6'10 or 6'11 now and not the 6-9 he was listed at as a teenager. But that doesn't really matter, he's an excellent P&R defender, he knows where he needs to be, he works hard and he provides really solid interior D regardless of which position he's playing.
The NBA is quickly moving away from traditional 5's anyway. I agree he'll struggle against big, strong 7+feet, 280+lb behemoths but honestly, how many guys like that are there that are good enough on offense to be a focal point? Not many. Most of the guys that big (DeAndre Jordan, Tyson Chandler, Dwight Howard) basically only score on put-backs, fast breaks and primarily rolls to the basket. Johnson's best skill is P&R defense, so without watching a whole bunch of old Raptors games I'd say that's a pretty overblown problem. He'll struggle more with skilled back-to-the basket guys like Sullinger, Lopez and Monroe but nobody's perfect.
Seeing how the game has evolved, I think it doesn't really matter if he's playing the 4 or 5. He's still probably gonna be our best defending big on the floor and there's just not enough skilled, powerful 7 footers good enough to exploit that match-up for it to be a big concern, IMO. We managed a middle of the road defense playing Zeller and Olynyk heavy minutes at the 5. If Amir can stay healthy, I think we can be easily top 10. With him and Zeller plus Mickey waiting in the wings, I think we still need a plus defending big in the future but were in good shape for this season. He's been a pretty under-valued pick-up both here and nationally. Interior defense was a huge weakness for us last season and Amir does a lot to improve that.