His fumble was costly which gifted the Cardinals 3 points and turned it back into a 2 possession game. So technically we can say Dak cost us the game, amongst all these events.
1) Dak's fumble (The only turnover that came at a critical time)
2) Greg's missed field goal (We may still have lost on that final Cardinals drive, but today they were the tying points)
3) Poor fake Punt coverage (Big momentum shift and terrible execution from Wright)
4) Questionable officiating (We couldn't find rhythm on offense and a big reason were drive killing holding calls that took good plays off the board. Then you had a questionable PI call gifting Arizona a 1st down, then the missed fumbled at the end of the game)
5) Playcalling (It really feels like Moore has a hit a wall with playcalling against solid defenses. We run the same stuff over and over and fail to establish a consistent running game. I wouldn't mind if Moore left to see what a new coordinator brings.)
6) Inconsistent throws (The Cardinals defense lined up a lot of guys near the line and made Dak very uncomfortable with those looks. Every QB has throws that get away, but Dak was off target on quite a few throws and really didn't push the ball down the field. Lot of underneath dink and dunk stuff. I think some of this is a result of #5 and why Cowboys receivers aren't getting as much separation as they should.