Although Win Share also shows Boozer as a good defender. I wish I had a login to synergy sports as that would be the best source of advanced stats. Hard otherwise to describe his good defense other than the eye test. But hes been a big part in shutting down high octane offensive guys in his time here. Guys like Steph Curry in February. He has lost a bit on defense, particularly quicker guys, but hes still a definite positive on D. One Synergy stat I did find is Kirk is 0.76 PPP in PnR situations. Now Thibs scheme is definitely a team scheme on D, but thats a good stat, and had I access to synergy sports I think you could find more advanced stats to back up his defensive reputation. Lacking that, just watch the games and see him against the top players and he makes them works and does a good putting them where the defense wants to put them.