Mainly the flop shots, although the lack of forgiveness for crucial approach shots (like Bethpage, hole 7) is a factor, too. On the par 5 Bethpage 4, for example, my 2nd shot frequently lands in the green-fronting bunker, with 15 yds or so left to pin. No matter what backspin and restraint I tried to apply when flopping with the Tour Burner Pro wedge, the flops either ended up rolling away from the pin to the other side of the green, or (not using full swing) they didn't even reach green, stopping in the rough or rolling back into the bunker.
Using my Tour Starter Gold 60° Wedge – I bought it extra for 1 dollar, so that I can later trade in the full Tour Starter set – I get exactly the result I want, even though this club has less back-spin and precision. (But far more forgiveness!) The flop shots from 15 yds range or so are neither too weak nor too strong, and I frequently manage to flop within a few feet from pin.