ok, I'll try to explain them as I see them...
Player 1 is a nice defensive Center. Not much in terms of offensive prowess, but he can block, rebound and defend the post. I'd put him as my starting C.
Player 2 is... well, a nice rebounder with some passing. But on the defensive end, he's rather weak. play him as C from the Bench.
Player 3 is a great inside presence, but can also defend a little on the perimeter if necessary, can drive into the paint and hit mid-range Jump Shots if he's shut out of the middle. His low Handling and Passing are not really optimal for a PF, but he's so much better on the outside than the other two that he's the clear favourite for the PF position.
Generally, play as PF only players who do have some talent on the outside - some of them can't pass or hit Jumpers, but they should be able to do at least one of the two, and defend against opponents who do.