I think Skulleader's pic explains it, the lift is greatly increased when the flaps lower and the nose rises. If you watch the vertical velocity it increases also. Can't say if it's over exaggerated or not as I've never flown an F-86 before but is pretty dramatic for sure. You see the same thing on the A-10 when on final, the FPM rises quickly when you lower the flaps, just not as dramatically.