What's interesting to me about Petruzelli is that from a future flexibility/negotiating/security/waivers/etc. standpoint after his ELC expires, his best bet would be to sign where the 21-22 season is the first on his ELC. Whether he sign's this offseason or next (or in between... I'll get to that later.), he has to sign for 2 years. Also regardless of when he signs, he has to have 3 seasons under contract before he could potentially become a Group VI UFA is he doesn't play enough NHL games (at least 30 minutes in 28 games) before the end of 23-24 or 24-25 (he's then eligible for UFA status regardless starting at the end of 25-26).
So if next season is the first of his ELC, he'll be looking for a next contract at the end of 22-23.
If in those hypothetical 2 year (or less... see later) he doesn't make much impact at the AHL level, he probably goes unqualified and becomes a UFA at 24YO to pursue other NHL or pro opportunities elsewhere.
But if he plays well and looks like he's still got a future in the NHL, he's probably got a good chance at getting a 2 year extension so his NHL team doesn't have to risk him becoming a UFA after 23-24 if he still hasn't played enough NHL games, especially considered he'd still be waiver exempt for those 2 additional years.
If he waits to sign after next season where his ELC starts with 22-23, he still has to sign a 2-year ELC, wait 3 years for the possibility of Group VI UFA status. The only difference would be that he would have 3 years of waivers exemption instead of 4.
As for the part I was referring to for later, the one thing he might be able to get out of the Red Wings if he goes for a 5th year in college is that they can sign him to his ELC toward the end of next season where the rest of 21-22 would count as the first year of his ELC which essentially:
-Gives him his signing bonus for 21-22 right away and likely some pro-rated NHL salary totaling what he might've made playing an entire year in the AHL on his two-way
-Burns the first year of the ELC, that he would've otherwise spent in the minors making the 2-way salary
-Burns a year of waiver exemption and one of the 3 seasons before he can potentially elect for Group VI UFA status
Otherwise, he waits to sign in the offseason, whether that's the contract the Rangers make up for every college UFA, or some other NHL team or opportunity he thinks is more favorable.
All that said, perhaps Petruzelli isn't worried about money or the pros and just wants to get his degree done before he moves on, or maybe he wants one last crack at the college level where both of his years as starter have been affected by the pandemic, and where his team lost the ECAC tournament finals in OT this past year and where the 2022 Frozen Four will be in his home state of MA. On top of that, another solid year at the college level can probably only help increase his stock when he goes to sign with the Wings or decides to sign elsewhere.