Bonk ironically, is the upside pick. If he fills out and improves his skating, he has the IQ to be a defensive mainstay.
An efficient, reliable D-man who can eat minutes (22+) is more valuable than an undersized 60 point forward.
The question with Bonk is how far can his physical skills can progress, size, skating, puck handling - because he'll maximize the impact of those skills.
Will he be a reliable but limited #4, or an all situations mainstay #2?
I think the pendulum has swing a bit too far toward flashy skill, but anyone who has watched the Flyers play defense the last decade can see the value of smart, reliable D-men who don't make mistakes by their absence!
I don't want a defense composed strictly of York, Bonk, types, but I think it'll be much easier to integrate the high speed, flashy new style D-men when you have a few guys who can give you 20+ minutes a night of reliable, competent, smart play. Just compare Provorov with every partner he had since Niskanen left town and his play last season paired with York, and you can see where these type of guys can elevate teammates. Or Sanheim with Braun.