Again, Mosely is learning a new position just as Greene has switched positions in his career. They've been working Mosely behind Ziemba so they may feel he's more suited for that side. As many have said, Gayden has battled injuries since he got here. I hadn't heard that, but if that's the case, someone else winning the job makes sense. And it just may be that while he's a mountain of a man and all that in JC, he may not be all that and a bag of chips against SEC competition.
The thing is with Greene, whether he turns out to be a stud at the position or not, I don't think we're really taking into account how this guy has transformed himself. He was recruited as a DE and labored in that position for a while and suffering through injuries. He was redshirted in 07'and didn't play at all in 08'. They moved him to the offensive line, getting in 2 games in 09'; however, if memory serves me, he's never been above that 270-280 range. Now, the guy has used the off season to beef himself up and dedicate himself to winning the position from all accounts I've read. I don't know if Greene will do squat once the season starts but he's sure impressed the staff enough to name him the starter.