Romo's turnovers cost Cowboys

Tony Romo made two key mistakes on Sunday -- but how damaging were they? AP Photo/Julio Cortez

Tony Romo's fourth-quarter mistakes really cost the Dallas Cowboys on Sunday night against the New York Jets. Romo had a Total QBR of 85.2 (excellent) through three quarters, but finished with a Total QBR of 62.9 (above average) because of his poor fourth-quarter performance, particularly two costly turnovers.

As a reminder, Total QBR is a quarterback rating that takes into account all of a QB's contributions (passing, rushing, sacks, fumbles, penalties) to his team's scoring and winning and summarizes them into one number on a 0-100 scale, where 50 is average.

Romo's two turnovers were a fumble on third-and-goal from the Jets' 2-yard line, with the Cowboys on the cusp of going up two scores, and an interception with the game tied at 24 that set up the Jets' game-winning FG. Since Total QBR weights plays in "clutch situations" more -- and this game was pretty close throughout the fourth quarter -- it may seem that Romo's poor fourth quarter should more than outweigh his great play in the first three quarters and bring his score down more.

But a deeper look inside Total QBR shows why Romo's performance still came out with a good score and not an awful one: