Every player has to learn to grind to some extent, this isn't pond hockey. People too quick to blame coaching for everything. He was a 7th overall pick in a draft that was weaker at the top compared to most drafts. He's gonna take some time and was hardly bust-proof on Draft Day. Honestly, his deployment is fine. They give him the highest share of offensive zone start time amongst Hawks defensemen, he is 41st in the NHL in terms of total Powerplay Time on Ice amongst Defensemen. They aren't intentionally throwing him to the wolves like Phillips and Crevier and watching him drown in a bad spot.
The issue with Korchinski is that with Murphy out, and throw Zaitsev being out as well who could have been a Backup, there isn't a suitable 2nd pair D partner for him. Both are natural right-handed defensemen, as is Jones, who is busy playing somewhere around 45 minutes a game as is and he/Vlasic give one real NHL pair. And more importantly, Korchinski will ideally play a similar "role" to Jones and so you'd like them to be on a different pairs. So that leaves him with Megna, a waiver fodder guy. And the Hawks are terrible in general so it's not like there's strong Forward support to prop him up.