Jeez, what are you expecting from him? To be Shaq? He is a very good F-C for a 8th/9th player on a contending team. He fills his role excellently and does nothing more or less than expected of him. He catches dunks, hustles and brings speed, athleticism and energy to the team on the court.
I expect him not to be a liability in all phases of the game that are not a wide open dunk. He doesn't have to be Shaq, he can just be Glen Davis or Leon Powe. But he isn't.
He's not "very good" as an 8th/9th player. As a matter of fact, it's probably a stretch to call him mediocre. Someone like Taj Gibson on the Bulls, Rasheed Wallace on the Knicks, or Spencer Hawes on the 76ers is a good 8th/9th player.
Wilcox is giving you the typical "10th guy to borderline DNP" type of performance.The problem is, we cannot afford this, mostly because he's the primary backup of a guy that's playing 28 minutes per contest.