Upshaw, Kapes (usually in the top of 16 and over) have huge slingshots. Upshaw is starting to go back to the traditional snap over some flack he has caught for slinging. Some kids are switching back and forth so it is hard to tell in the rest of the 16+ group.
If the gate is “flexy” when a rider pushes off of it to get the bike to move backward the gate will move and can throw off your balance and in turn screw up your timing as you are fighting to keep the bike up. If they are in gate 1 or 8 (further away from the air ram) the gate moves more. A lot of times it screws people just because you see the movement in your periferal vision.