I think the big issue with Lance being #2 on the depth chart is that you really change the entire offense with him in the game. Its a lot more quick reads and throws, RPOs, designed runs, etc. You really want your backup to be able to come into a game when needed and run an abbreviated version of the same offense so the other 10 players on the field dont have to change too much from the game plan they've prepped for all week. I think if Dak were to miss an extended amount of time you'd see Lance get starts over Rush as they'd have time to install packages specific to what Lance does well. I think Rush is the guy to get you through a game, but also isnt a legit multi game starter in this league either. Lance is obviously unproven here, but does offer the upside that Rush doesnt.