Eh, it's more representative of failures on first and second down. Not that that's better, but your third-down offense will always be bad when you need 8, 9, 10 yards.
All Dallas 3rd Downs
1st QUARTER
3rd & 16 @ DAL 48 Incomplete Pass (Led to Dallas Punt)
3rd & 1 @ DAL 43 Elliott runs for 4 yards (Led to Dallas TD)
2nd QUARTER
3rd & 3 @ DAL 32 Prescott runs for 6 yards
3rd & 7 @ LA 35 Incomplete Pass (Led to missed 53-yard FG)
3rd QUARTER
3rd & 10 @ DAL 44 Completed 11 yard pass
3rd & 4 @ LA 39 Prescott sacked for -8 yards (Led to Dallas punt)
3rd & 9 @ DAL 39 Incomplete Pass (Led to Dallas punt)
3rd & 6 @ LA 15 Incomplete Pass (Led to Dallas 33-yard FG)
3rd & 6 @ LA 14 Elliott runs for 3 yards (Led to failed 4th & 3 Prescott passed for 2 yards)
4th QUARTER
3rd & 5 @ DAL 17 Incomplete Pass (Led to Dallas punt)
3rd & 13 @ DAL 18 Prescott runs for 12 yards (Led to 4th & 1; Elliott runs for 4 yards)
3rd & 20 @ DAL 34 Incomplete Pass (Led to 4th & 20; Incomplete Pass)
Average 3rd down conversion needed was 8.3 yards.
4 of the 12 3rd downs were within LA territory and of those 4 3rd downs within LA territory Dallas failed on ALL 4 of them and came away with only 3 points as a result.