Sure is hard to tell even with his significant snaps that he's had. One game I thought he looked very promising, another game I thought he was very inaccurate with his throws. Only time will tell I guess. Tools seem to be there. Although we don't hear much about the intangibles, what his leadership level is, etc. I guess until it's 'his time' that would be hard to access.
I would think rhythm is what would play a big part here. Additionally, when Dekkers has gotten in, the game has already been in hand (except for Iowa). The play calling may be more specific to what they want Dekkers to practice rather than trying to move the ball as you normally would. The entire offense could have a different look next year based on the strengths of the players. Dekkers is a very different beast than Brock Purdy - He's a big body, with a big arm and is very athletic for his size.
Of course we'll all have to wait and see when he gets his first start (against SE Missouri State) next year. But I'm excited to see what he (and the rest of the team) bring next year.