Once Demaryius Thomas crossed the line to gain at the Dallas 14 yard line with 1:50 to play, the Dallas defense should have intentionally allowed the TD. With 2 timeouts and 1:40+ to play, they would have had a better chance of winning than allowing Denver to choke the life out of them and kick an easy FG for the win.
That's based on this analysis of when teams should intentionally allow a TD when tied.
After Thomas gained a 1st down, Dallas correctly called a timeout setting up a 1st down and 10 at the Dallas 11 with 1:49 to play. This chart illustrates Dallas's chances of winning based on field position and time remaining with 1 timeout left.
The strategy of forcing a FG is highlighted in red. It's worth about a 0.01 or 0.02 WP. The strategy of allowing the TD is highlighted in blue. It's worth about a 0.12 WP. Getting the ball back with all four downs and 1:45 to force overtime isn't where you want to find yourself, but it's twelve times better than hoping for a FG miss.
Denver appeared to be completely cognizant that they had Dallas in the field goal choke hold, but only after the timeout while Manning and Fox had time to think. I'm not sure Demaryius Thomas would have been so alert in the midst of play. The instinct for the goal line is too great—see Bradshaw comma Ahmad in Super Bowl XLVI. I don't have access to the tape, so it's not certain if that was even a possibility—but that's when Denver should have been prepared to allow the TD.
The right thing for the Dallas defense to do is to instruct their players prior to the snap on 1st down and 10 from the Dallas 24 with 1:57 to play: If Denver gains a 1st down, miss the tackle.
Denver was able to gain another 1st down, which was the absolute worst possible outcome for Dallas. That final 1st down made it a no-brainer, and Denver milked the clock and kicked the FG for the win.
Brian Burke is the founder of Advanced NFL Stats, and a former Navy F/A-18 carrier pilot.