I don't know if he's a better defender as in he knows how to defend better (like Rashon for example). He has a much better reach and is quicker which allows his defensive position to be better just from a physical aspect, but I wouldn't say he's MUCH better. A minute point, but either way I think he should be in there.
He is a much defender in that he understands the concept of TEAM defense much more than Huluska. Haluska gets up in his man's grill every second, even 40 feet from the ball. He NEVER helps and can't fight through a screen. Boozer seems to understand the 'ball-you-man' concept much better and is able to create more havoc that way...
This gets me to a MUCH bigger I problem I am having with our guard play which came into play last night... I think I might post it on another thread though...