​The Cowboys' offseason has been about Zeke Elliott's off-the-field concerns and Dak Prescott's development above all else.

But dig a little deeper, and a key story has been brewing in Jerryworld.

Who backs up Dak?

Before the preseason, Kellen Moore was the anointed backup coming off his busted hand, but he hasn't looked great in preseason appearances, completing just 54.5 percent of his passes and throwing just one touchdown. Because of those struggles, the Cowboys are looking around for a backup signal-caller, who may already be in the roster. 

​​Rookie quarterback Cooper Rush, who played his college ball at Central Michigan, has been getting some second-team reps, indicating the team isn't happy with Moore's performances. Oddly enough, draft expert Lace Zierlein of NFL.com said Rush's NFL comparison was...Kellen Moore. 

Rush has completed over 68 percent of his passes this preseason, while throwing for 283 yards, four touchdowns and no interceptions in three appearances. 

The team could look outside its current roster to add quarterback depth, but given Dallas' views about Moore, some kind of change seems imminent. 

​​If all goes well, this situation won't matter for the Cowboys. But should Dak go down with an injury for a short period, the team's going to need another solid option to run the offense. As of now, it doesn't seem like Kellen Moore is that guy.