Trade Breakdown:
-Detroit acquires Alex Debrincat with a sign and trade, 8 year extension.
-Ottawa acquires Alexis Lafreniere (RFA).
-NYR acquires compensation for Lafreniere that is anchored to offer sheet compensation, but exceeds what they would receive in an offer sheet.

In an offer sheet scenario, the Rangers are likely to receive a 1st+3rd pick. It might be from a contender. They won't be able to use it until next season. Through this trade, they get a mid 1st round pick (17th) and two future 2nd round picks instead of a possible future late 1st and a future late 3rd. They also receive Tyler Boucher, who does not have a lot of value (maybe a 3rd-7th type value). He was originally chosen 10th overall by the Senators. The Rangers were rumored to want him with their 1st round pick at the 2021 draft. Zadina is a throw in. Detroit retains on Zadina to put him at the 1.125M buried cap threshold. Which means if he doesn't make the NYR roster, he will not cost them anything in cap to bury. While Detroit burns a retention spot, they were likely to bury Zadina anyways, so there are no cap implications since they would pay the difference between his cap hit and buried cap hit regardless. Zadina is a big name since he was selected high, but at this point he is a bust who may end up on waivers if he stays with Detroit.

In terms of Detroit, it's simple. Debrincat wants to play there. They get him for 1st and a future 2nd. You can swap out the 2nd with a prospect who is worth a future 2nd or a comparable 2023 3rd. I am simply not familiar enough with their prospect pool. Consider that 2nd as placeholder assets. (Ditto for Ottawa's 2nd). Detroit also takes Joseph, who likely has (at best) neutral value and possibly negative value. He is not a bad player, but he is signed with too much term for what he has shown. There is the Yzerman connection there from his time in Tampa.

Ottawa's new owner acquires a big French Canadien star to help market the team around to the Francophone population in Orleans and Gatineau. Lafreniere likely costs 4M-6M on a bridge or mid-term deal. Similar to Dach, but probably a bit higher because of his stature. Shedding Joseph helps make that deal work cap wise, while still leaving space open for Ottawa to acquire a goalie in a different trade.

Take out Joseph and sure

While I don't think Debrincat is going to go for a lot, taking Joseph is part of the reason it's a 1st+future 2nd (equivalent to a current year 3rd) for an extended Debrincat.

The Joseph contract is bad, but we have inexplicably seen worse forward contracts moved at the deadline - and there is possibly a connection between Yzerman and the player. I don't know his entire draft/development history, so maybe he wasn't one of Yzerman's guys in Detroit. He's a perfectly fine top 9 forward, he just has a bad contract in the context of the flat cap. Ottawa would need to shed him to pay Lafreniere. It seems like a sensible match.

Either that and add something that has value or Ottawa retains 50% on him. The retention on Zadina needs to be removed too.

Considering that Mathieu Joseph welcomed Larkin back from his stint in a neckbrace by boarding him; I don't think he'll be joining the Red Wings any time soon.