They moved swing guard Joe Looney to start in Frederick’s place, leaving a hole.
The Cowboys thought they had filled that spot with a trade with Kansas City for guard Parker Ehinger last week. But Ehinger injured his knee in practice Wednesday.
He did not practice Thursday.
The Cowboys worked out Xavier Su’a-Filo “just to see if he can help us in any way,” coach Jason Garrett said at his press conference. Su’a-Filo was a second-round pick of the Texans in 2014 and started 41 games — 40 at left guard and one at right guard — in…