WALTHAM — If you needed any proof that Fab Melo still has a lot to learn (and prove) to make it in the NBA, and that D-League stats don’t carry over to the NBA, we submit for your review the following evidence.

Celtics captain Paul Pierce took the opportunity Tuesday before practice began to teach the rookie big man out of Syracuse a thing or two about playing on the low post.

With Jared Sullinger out with season-ending back surgery, Melo was called up from D-League and played just three minutes against the Magic with a steal on Friday but did not seen any action Sunday.

Tuesday we saw a small reason why. Pierce noticed Melo working by himself on low-post moves and came over to give him some real resistance.

Melo missed a shot, double-dribbled and then, while defending Pierce forced a fadeaway that was off-target. But Pierce objected, calling a foul. The next two drives to the basket were baby hooks that found the bottom of the basket. Pierce walked away triumphantly, shouting “all day” to Melo, Celtics coaches and anyone within earshot.