Michkov will be fine. People want to force feed him, but that won't help him develop.
Kucherov started at 20 years old, played 52 games at 14 minutes a night, Next three years they gradually increased his workload and responsibilities.
Watching Michkov, he doesn't know how to play 5x5, he's great in the O-zone, but free lances a bit, but lost in the neutral and D-zones. Which is not surprising, in the KHL at 18 he was playing on a bad team where he was the offense. Had he played on SKA, he'd been playing 12 minutes a night on the 3rd line and would have been benched if he didn't play defense. He learn. It'll take time.
Brink is 23, and you can see the improvement from last season, skating faster, working harder on defense and the back check, learning to use his body, etc. Still not great at even strength, but improving.