Even if Paulsen knew exactly why they didn't defend well (he probably won't until he reviews tape), I doubt he'd say it in a press conference. Just like hes not going to discuss the status of someones playing time or the status of Grayer. He says certain things during press conferences, usually in a loss he credits the other team for doing something well, and states what Mason didn't do well.
I'm guessing he's done press conferences for a long time and hes not going to change his style.
He also, as we know, is a very "practice like you play" sort of coach. So if the guys are going full speed in practice and doing well, he expects it to translate to the court. He isn't going to know why it doesn't always move over, but all he can do is continue to keep pushing the guys to improve. If you expect him to throw a chair or yell about it being his fault in a loss, you probably will never see it.
Onto LaSalle which has now become very important, because Mason doesn't have room for any other crap performances if they want top 4.