You can count on a trick play every time Utah drives inside the 40. Part of the reason they don’t work is because the D has seen them on tape and is aware that something is coming. The other reason is that they aren’t based on any other plays Utah runs.
Vele never fakes a reverse so it’s pretty obvious something is up when he heads in that direction. In fact, Vele never is used on a screen either so he is the worst person to run something behind the LOS with. Not because he can’t throw but because the offense hasn’t set those plays up during their normal scheme. If you run a tunnel screen every once in a while with Vele, then there’s a legitimate reason for him to be moving towards the pile and maybe you can catch the D off guard.