Being able to defend on the perimeter alone does not make someone a small-ball center.
If that someone is 6'10, then it makes him the perfect small-ball Center. That's the whole point of using small-ball Centers: switching ball screens on the perimeter and defending multiple positions. Btw, this is exactly what Theis does for the C's. He's a very versatile defender.
They were also two of the best shot-blockers in the history of the game, and were strong/smart enough to defend monsters like Wilt and Shaq. Simmons is not at all like that.
Ben Wallace could defend the post against the likes of Shaq
If there were a guy like Wilt/Shaq in today's NBA, we would be having a very different conversation. There is no need to start a traditional big man anymore. Slow-footed big men get killed in the pick n roll/pop.
Simmons is a wing. He plays like a wing.
Only because he plays next to Embiid. People keep saying that Simmons cannot play off the ball. This is true in Philly, but it wouldn't be the case in Boston. I bet Simmons would make a terrific roll man. Whenever he'd be off the ball, he'd be setting picks on the perimeter with a view to rolling hard to the basket. I'd love to watch the Smart-Simmons pick n roll!
I'm rooting against Houston so hard for this reason. I do not want to see them succeed eschewing a center entirely.
I'm rooting against them too, but you are comparing apples and oranges here. PJ Tucker is 6'5 for crying out loud! Again, Simmons is 6'10!
I hate D'Anthoni's style of play. If you ask me, the Rockets are a traveling circus (at least prior to the bubble cause they don't travel anymore

). No way they make serious noise in the playoffs.