He has said on multiple occasions that it is partially because they don't play zone in the NBA, so he plays a system that helps set them up at the next level. The thing about Cal is he can recruit at the top level, and what comes at the top level is generally a combination of size and athleticism, which is why our teams have been consistently some of the top defensive teams in the collegiate level. The real problem is, there are times where switching to it on teams that are pure post big men coupled with slasher guards, would absolutely destroy them. UCONN is a great example both years. You just have to look at all their losses, Louisville absolutely destroyed them and so did several other teams with zone prior. That being said it is a hard thing to drop on a select few teams, when he has taught defense an other way the whole season. So he sticks to what got them there instead of trying something that would probably work better in select situations, because his team isn't used to it and he is unsure how they would respond to a change that late to the game plan.that late in the season.