I think this is the last year we can even hope Hertl becomes the player we have all seen dominate at times. If he doesn't significantly improve this year then I think he is just winger he is used as now and will never become the #1 or 2C we all hope he becomes. He is starting to get a little old to be talking about potential.
He's already pretty much been the 2C when he's with Couture. During the flow of play they are often alternating their roles depending on positioning. And since he does take the bulk of the draws, he's got that going for him as well.