Even the most experienced Ds can be fooled by a play fake. In the 06 OSU/UM game, a very experienced UM D that was ranked in the top 2 IIRC, bit hook, line, and sinker on a brilliantly executed PA pass, resulting in a Smith to Ginn TD. There's a good reverse angle shot at the 50sec mark. You can see the safety moving up to play the run, allowing Ginn to beat the CB to the inside. The RB on the play? Chis "Beanie" Wells.
YouTube - Troy Smith vs michigan 2006
I expect PCP will try to shut down the run, and make our O one dimensional. I actually expect every team will use that strategy. Stopping Beanie (and the other backs) is a lot easier said than done. As long as TB is not forced to throw on every down, I don't see him as a liability.
I see what you're saying, DBB, but the effectiveness of the RB does have an impact on the PA. I would say that establishing the run is the most important factor. If the front 7 can shut down the run without safety support, the DBs have no reason to worry about anything but their assignment. The DBs don't have to be completely fooled on the PA, as long as they hesitate or take a step up, the WRs should get separation.
You are dead on about the PA being a team effort. Even the WRs have a part to play. Michael Jenkins was especially adept at selling the run by faking a block before continuing his route. The O-line's job is particularly difficult, since they have to pretend to run block without moving forward. I heard Spielman say on the radio that he always knew when a PA was coming by watching the OL before the snap. He couldn't put his finger on anything specific, but he claimed he was never fooled in college or NFL.