With 4 rushers blown by you (which the Cowboys repeatedly did because Mac set so deep and tried to spin out), you have one rusher in front of you and you have Onwenu with a hat on him. So what do you do? You run past Onwenu's block and then panic. Instead of stepping up into the pocket and setting your feet to look for a throw, which buys you another second or two, you disregard the blockers and step right into the oncoming rusher's path.
I knew we'd have a tremendous downgrade in this part of the game from the guy who was the greatest of all time at commanding the pocket, but we ended up with someone who is one of the worst at it in the entire league. Zappe does not have the physical capabilities to play in this league but you actually see him step up into the pocket and reset his feet to look for a throw (which he can't make).
There were 5 pass rushers coming at Mac in this play, 5 Patriots OL, everyone else was out, including Rham and the one LB on Rham. That means we had 3 WRs out there and 1 TE. So 4 pass catchers against 4 DBs and 1 LB.
Mac should be able to find someone open with an extra second or two here.