Shaq's issues are not related to athleticism or skill. They are mental. He has labile confidence, which could go either way. This year is a transition year for him mentally as someone that is being counted on. I believe this year he will have up and down stretches, and next year things will click fully with him. 9 points 4 rebounds this year, 14 and 5 next year.
Strickland has a soft physique, no muscle tone, no vertical, he's slow and has no explosion. Plus he hasn't played in 2 years. He is supposed to offset all that with soft hands and touch, but his hands are too weak to play in traffic. Unless he becomes almost exclusively a jump shooter (from the elbow or top key), he will be a nearly worthless 4 year player.
Yes, he needs to get in better shape but you're off base about him being a jump shooter for 4 years. He has a knack, at least in drills and practice, of putting the ball in the basket. It may take a year but Strickland will contribute at some point. I'm not saying he will be a dominant center, but he will contribute.