Crawford has been beaten out at 3T by Collins and Irving, that's why he plays out of position.
You're letting your bias show:
From espn.com:
FRISCO, Texas -- When the
Dallas Cowboys drafted
Tyrone Crawford in the third round in 2012, they envisioned him as a defensive end in their 3-4 scheme.
A year later, they moved to the 4-3 scheme and Crawford missed the season with a torn Achilles. When he returned in 2014, the Cowboys moved him to under tackle in Rod Marinelli’s defense and were convinced they had found him a home, rewarding him with a five-year contract before the 2015 season.
Injuries elsewhere along the line forced Crawford to left defensive end, taking away his strength against interior linemen and putting him against tackles in space. It has led to outside critiques that have been unfair because the Cowboys have not used him in a way to take advantage of what he does best.