Carlos Boozer has had some weak performances in the playoffs but he has also had some very strong performances in the playoffs too.
Boozer was terrific in 2007 against Yao Ming plus Golden State's weak front line, and, very good against Duncan's Spurs in the Conference Finals. The Rockets and Spurs were both high level defensive teams too.
Next three years Boozer played against the Lakers and all their length. He struggled in those matchups for the most part.
Struggled a lot the first year. Played pretty well the second year (three very good games, one so-so game, one bad game). Then played very well against Denver (Kenyon Martin and Nene) the next year and then struggled again against LA's length in the second round. Since Boozer has gone to Chicago, he's done nothing in the playoffs.
I think there is a strong and clear argument to be made that Boozer can be taken out of games by teams that have lots of length and solid quickness inside. But aside from that, his playoff record is pretty good.