ENGLEWOOD, Colo. — In the week before the Broncos’ third preseason game, at Washington, undrafted safety Dymonte Thomas was told he’d be an insurance policy. Su’a Cravens was still out with a knee injury, Will Parks had his knee taped up after suffering a contusion and Thomas was next in line at dime backer.



Get ready, Joseph told him.



So in two days of practice, Thomas crammed, failing more often than not.



“I was making so many mistakes out there,” Thomas said. “VJ came up to me at the end of practice and was like, ‘I’ve never seen so many MEs (mental errors) by one player before.’



“Just to know that he relied on me, I had to learn it as fast as I could just to show him that he could trust me.”



The Broncos play the majority of their defense in subpackages, so the fifth defensive back on the field is a critical one. For Thomas, perhaps no game was bigger in his young...