Why was Gilkey starting?

I had previously stated that it was hard to see Gilkey being that much worse than EDS, but boy was I wrong!  What I can't understand, and I'd be curious to hear from PR, is why the Bucs decided to start a player who had never played center before (ever).  Given his already poor play at guard, it seems crazy that there is so little depth that you have to start that crap.  Like every team, the Bucs have a backup center.  It is just shocking to me that even given the poor player evaluation that Gilkey would start at center.  One can assume he doesn't play well in practice either.