"Is Vance Joseph in denial about his bad QB, his bad team and his bad adjustments?"

"Denial" assumes he knows the truth. You're giving him too much credit.

Prior to becoming head coach, the highest position Joseph held was a coordinator position and that was only for one year. All his other experience was as a position coach. As Defensive Coordinator for the Dolphins he led the team to the 31st ranked defense.

He's not experienced enough to deny anything. If anything accuse him of incompetence. He's hardly fit to be an equipment manager let alone a head coach.

Denial and incompetence aside, Joseph doesn't have the power to make any decisions. If Siemian gets pulled, what does that say about Lynch and ultimately Elway?