I was actually thinking about this earlier today. I think the Allen Crabbe trade was a case of addition by subtraction. The Crabbe fans said we'd miss his 3-point shooting (we haven't - we're 2nd in the league at 3FG% = .381, last year we we're 7th at .375), but last year he was the worst defender on a bad defensive team and was 3rd on the team in total minutes played. That hurt our overall defensive rating.
This year his minutes have been replaced by Connaughton and Napier. While Connaughton is not a lock down one-on-one defender, he has much better defensive awareness than Crabbe, He doesn't lose his man or blow rotations the way Crabbe did. Napier, on the other hand, is a great defender in spite of his diminutive size. He has quick, active hands and really puts a lot of energy into harassing his man. He get's a lot of steals and deflections, and surprising gets posted up very little. I think this is a major reason for our improved perimeter defense.
But, there's more to it than that. On the inside, we have a full year of Nurk, which also makes a big difference, as well as a defensive minded rookie coming off the bench. We have a healthy Ed Davis, and Dame and even C.J. are putting a lot more effort into their defense this year. Evan Turner seems to be taking a great deal of pride in his defense this year. I give Stotts credit for getting these guys to buy in on the defensive end, and having the guts to play a rookie who struggled on offense early.
This defense keeps us in games when we struggle to score. Defense and rebounding wins championships. Hopefully, the way we have been playing lately will continue into the post season.
BNM
