You are seriously taking a sample from one player of a totally different style of play and then transferring it on to another...and actually two players who never stepped foot on Mackey at the same time? Come on man. As good of a shot blocker as JJ was, he wasn't nearly as good of a paint defender as AJ was. Do remember that VCU team made it to the Final Four and unfortunately we were in the way of that run.
Also, why do you just assume that our PG is going to play some type of ole` defense next season? Thompson was a true freshman last season and seemed to play pretty good defense, especially late in the year. He is known as a hard worker and a guy who follows what Coach Painter asks him to a 'T'. With that in mind, you have to think he is going to take the steps that Coach Painter and the staff want him to take to improve himself on the court. In all honesty, the team will be just fine with PJ running the point if he can simply improve lateral quickness and strength to be able to body up on opposing PG's in the half court. For a true freshman, PJ did a good job of running the motion offense and setting up teammates within the offense while also being able to knock down some open shots...that is literally what Coach Painter wants from his PG's. As good as Lewis Jackson was, that describes him exactly and why he was such a good PG and why Ronnie Johnson was just flat out terrible in his time at Purdue.