As crazy as this may sound, I actually believe Splitter is better at sealing his man in the low block than Duncan is, at this point in his career. If nothing more than the fact that he usually does it so much more often.
In fact, I've actually seen Splitter seal his man on numerous occasions, on consecutive possessions, without ever seeing the ball. Of course, he's always there to try and clean up the garbage, off a missed perimeter shot.
I believe Sean is on point with him comment. Sean has also criticized the other players for not getting it back into Splitter on a re-post, after a pass out. Parker is usually the best at deliberately trying to get Splitter the ball. The other players? Not so much. Those other players absolutely MUST look to feed the post when Splitter is down there. They're just having too much success down there.