Obviously Rex Grossman's unimpressive play, Sav Rocca's botched hold, and many other factors contributed to this loss. But the 3rd and 21 completion to Dez Bryant that saved Dallas' game-winning drive is the most painful failure because it was self inflicted. A reckless, show-off play call in the worst possible situation quite likely cost the Redskins a win.
Dallas lined up with three receivers (counting Jason Witten in the slot) and two backs in the backfield to block. Jim Haslett blitzed eight guys - including both LaRon Landry and Oshiomogho Atogwe. That left three DBs in man coverage with absolutely no help if they got beat. In a crucial situation where preventing a first down is all that matters, that's just unacceptable.
DeAngelo Hall, naturally, got paired up with Dez Bryant. Bryant, I probably don't need to point out, is known as an exceptionally dangerous receiver. Bryant runs a great route here - he presses to the outside just enough to get Hall to turn his hips, then when Bryant breaks back to the middle it's all over.
Blaming DeAngelo Hall for this outcome just doesn't make any sense. Did he get beat here? Sure. But whenever you man up on an athletic receiver there is a chance of that happening. I don't care how good your corner is, Dez Bryant will win a decent proportion of these matchups. I should also point out that despite getting turned around Hall was beaten by about a step, and did a nice job of recovering. Against a lesser corner that's a touchdown, not just a first down with a BS facemask tacked on.
Pinning it on Hall doesn't give Bryant credit for making a great play, and it unjustifiably absolves Jim Haslett. Haslett put his man in a position with a high chance of failure, and in a situation in which such a failure would have catastrophic consequences.
A blitz on that play was reasonable. There's no sense in giving Romo too much time to stand around and let one of those receivers come open deep. But send a linebacker or two after the guy. The one thing you just can't do is take both safeties out of the play and make it an all or nothing affair. In this game situation and with that down and distance, there was simply no justification for an eight man blitz other than to score a dramatic kill shot on national television.