Right now, none of the top 6 Ws available this summer have the numbers to get as good a pay day as Rust in free agency. Unless Rust wants to offer a big discount (or waits until the '22 offseason to sign and has a really bad 21-22 season), a guy we sign this off-season is almost certainly cheaper than Rust from '22 onwards.
Which is not the main reason you do it.
It's about there being three roads on what to do with Rust. One is to lose him for nothing in '22. One is to reup him at a cost that may not match his future contributions. The last is to trade him for assets. If the latter is the plan, it has to be this summer. It can't be summer '22 because he's a free agent. I guess you could sign him this offseason and trade him before his new deal kicks in, but he's going to be a far less attractive asset on that sort of money. And this summer, Poulin isn't ready. It's either make do or mend from within the roster - promote Carter maybe - or sign a free agent.
The fact that the free agent signed this off-season has a good chance of being an equal or better contributor for their cap hit from '22 onwards does factor in from this point as we're talking about whether the team can afford to lose Rust from a contention standpoint. Nobody likes the idea of trading him for assets if it hurts us as a contender but if we can get a reasonably priced UFA it changes a lot.
But basically it comes down to which of the three options is the most appealing. I think there's good reason to think losing him for nothing and fat UFA contracts are both unappealing options. Trade and replace mightn't be fantastic either, but if the other two options aren't great it should be an option on the menu - with the quality and cost of potential UFA replacements being a big part of whether to go there.
