you missed the years Dejuan Blair, Matt bonner, Boris Diaw, and Antonio mcdyess
Started next to Duncan. Splitter only made 151 starts in 5 years. He spent more time as Duncan's backup. And no center after David Robinson ever played more than 30 minutes, Duncan was getting significant minutes at the 5 while he started as the 4. In reality, whether you call him a PF or a C is pretty irrelevant. He played significant minutes at both. For reference, basketball-reference.com lists him as playing 69% of his minutes at C. Data only goes back to 2001, so the number would be lower if it included the Robinson years. But clearly he's played a lot of center.
Again, call him a PF if you want, I have no problem with that, I look at him more as a center. His size and style of play, especially as of late, are more in line with what a traditional center looks like.