Since when can you teach size in middle school? Part of the NBA defensive game is SIZE, which D-Lee has NONE OF at the Center position (Not to mention...he IS A CENTER on this team...). Strike One against him as a defender.
Since when can you teach athleticism in middle school? If you want to be an elite NBA defender (ex. Josh Smith), or even a DECENT NBA Defender (ex. Trevor Ariza) then you have to be able to not only jump out of the freakin gym, but also have speed, agility and lateral quickness to stay in front of opposing players, or contest shots. Strike Two.
You may be able to teach the 2-3 zone to a bunch of 7th graders, but you can't teach a player how to put himself in the right place defensively in a game situation, and David Lee has proven that. Strike 3.
Since when is defense the easiest thing to learn in basketball? Who made you the NBA scout here...because last I checked, only the elite defensive players can control a game defensively, and only the elite defensive teams win championships in this era of basketball. Obviously it isn't the easiest thing to learn, and learn well, seeing as only the very best can play defense the right way. David Lee is NOT an elite player (top 20), and will never be a force defensively.