[holyfield5]

when you dont reraise PF you are letting him take control of the hand, you can no longer play your hand for value as an overpair.

You get folded out by a lot of hands you beat on many flops, reraising preflop makes the hand easier to play which is +EV.....or it takes the pot down there and gets you about as much as if you took it down with a donkbet/cbet on the flop in a raised pot, which is what happens most of the time. If he only calls you are pretty much good most of the time anyways as he will be playing a pure guessing game(like you are now).