I think it's obvious to everyone at this point, including 4-time champion and one of the best to do it ever, Gregg Popovich, that Splitter deserves and needs more minutes. Additionally, he truly is better than Bonner will ever be and has ever been at everything but shooting the basketball.
HOWEVER
I am trusting in His Holiness of the Church of Popovich, Coach Pop, and in doing so, wonder what logical reasoning backs his limiting Splitter's minutes.
A few possibilities spring to mind. Some could be true, or none, or others, or maybe all, I really don't know.
One, Pop could be saving Splitter for the play-offs. Although the roster is already injury ridden in this early season and lacking capable big men as a whole, Pop truly may still believe there's hope for this Spurs squad winning a le if Splitter, chief among others, is healthy and capably steps up his game in the postseason. Tiring Splitter out early, or him suffering an injury, or worse - such as having him hit some sort of unpredicted "wall" mid way though the season and lose his confidence in Pop's barking - could all spell disaster for the Spurs. The Spurs have a tough road ahead without Manu and delicate management of the situationals is obviously quite important.
Two, Pop could be simply worried about the big man rotation and is overplaying Bonner to compensate. From the most logical standpoint, an injury to Bonner would be the best possible scenario out of all four primary big men being injured. For example, Blair's offense is needed and his learning needs continue; Bonner, on the other hand, won't be getting any better any time soon. In fact, with every passing day it has become clear that he is worse. Ultimately, Pop's conservative rotations regarding Splitter could leave the rotation feeling decently fresh come playoff time without a major move. Considering the cir stances, this scenario is quite possible.
Third, Pop could be exerting his influence as a coach on Splitter. Not in a bad way, just in a way that lets Splitter know whose boss, and what he must continue doing to earn meaningful minutes often. Pop and the Spurs organization in general has proven stubborn in its mandates, especially concerning a player's general respect for the coaches, fellow players, and especially townsfolk. Splitter seems like a great guy but we don't know exactly what goes on in the background, and Pop's actions may be reflecting unknown events in the locker room and beyond.