Montreal trades Paul Byron and Noah Juulsen to Calgary for TJ Brodie and Michael Frolik.
Calgary fends off offer sheets to Matthew Tkachuk by freeing up more than $5M in cap space, giving them about $10M to work with. They re-acquire Byron to play top 9 and PK, add speed, secondary scoring. At $3.4 M for 4 more years, the Flames gain cost certainty. They add Juulsen, who slots in on the 3rd pair and gives them another young, cost certain player that they have team control over.
Flames give up 2 UFAs in Brodie and Frolik. Frolik fell out of favour under Peters, playing around 13min a night. He's likely the first to go when Tkachuk gets signed as he's too expensive for that role. Brodie is a UFA and with the expansion draft coming, one of Hanafin, Giordano, Hamonic, or Brodie would be likely left exposed. Allows Calgary to get ahead of this and start turning over the D to Andersen, Valimaki, Juulsen, etc.
Montreal gets a true top 4 LHD that is mobile and can play big minutes. I know he's more comfortable on the right side but this proposal banks on the Canadiens pro scouts determining that Brodie can play at a high level on the left side. Frolik is a negative asset in the trade due to his cap hit but likely fills a top 9 or depth role just fine for one year.
If Brodie works out you can sign long term and keep team control. Same with Frolik, really, though he's likely to have to take a paycut, whereas Brodie would see a significant raise.
Flames clear cap space, allowing them to sign/match Matt Tkachuk up to $10M, gaining 2 players under team control. Montreal gets the best player (on an expiring contract) and cap flexibility.
I like the idea of this trade as a pre-emptive move made to insulate the Flames against an offer sheet. But it could work in the 7 days after an offer sheet is signed as well.