I’ll assume you mean Williams, but I think Alexander was a very solid contributor, Fulk (when healthy) has also been solid. If you count Pons as a big man, he was solid. Burns could have been if he could have stuck around and stayed in shape. He obviously has talent. Corey Walker remains to be seen what he could have been for us, but he certainly has pedigree.
On the flipside, Kent wasn’t good. Plav hasn’t materialized. Pember was a reach, though probably no more (less, actually) of a “big man” than Pons. Derrick Walker was decent in spurts as a freshman and then never took the next step, and left. Nkamhoua is still an unknown, but I don’t have great hopes.
Probably a little unfair to say he’s only hit on one guy in 6 years, but there have certainly been more misses than we’d like to see in the post.