The run game not being good is bogus. We just wouldn't commit to using it, even when it was working. We were typically top half in the league in average yards per carry but bottom half of league in rushing attempts. We even did well converting 3rd and short running the ball contrary to popular opinion.
Here is an article in 2013 wondering why the team won't run.
https://www.si.com/nfl/audibles/2013/12/17/the-all-22-cowboys-run-game-demarco-murray-packers
http://www.nfl.com/news/story/0ap2000000299618/article/packers-happy-cowboys-abandoned-running-game
"That's just who they are," cornerback
Tramon Williams said. "They run the ball really well against everybody they play, but they just never stick with it."
"Oh, my God. It's the best zone scheme in the league," Pickett continued. "The last four weeks, nobody could stop it -- their zone scheme.
And they gave up on it. We're just happy they did. We were, like, 'OK, we'll take it.'"