Definitely need another big, maybe two. What if Chukwu decides he wants to move on. He will graduate, no?
As for Sidibe, it is premature to say his career is in jeopardy. However, tendinitis tends to be a chronic/recurring problem for many. As someone with a medical background, I would hook him up with a naturopath and see if there are any dietary changes that can be made to help with inflammation. He's originally from Africa which has far less processed food than here in the states. I'm not saying that's what's causing Sidibe's health issues, but it's an element that's worth exploring.
So... like I was saying, we need to be prioritizing the center position. Marek has subbed in remarkably well against smaller teams,but I don't think it's fair to him or his development to expect him to play the 5 on anything more than an emergency basis.