Okay Islanders fans, let’s discuss what it will cost to move salary in this era of hockey. In this trade, you are giving away a first round pick, a young defenseman with some NHL experience, and a veteran who is getting paid too much for his current value. To find a team that can and will take the 6 million contract over the next two seasons is going to be very difficult, but Detroit is a team that fits the mold.
Detroit currently has Alex Biega, Troy Stetcher, and Filip Hronek/Jon Merrill posted on the right side for this upcoming season which is hardly anything to brag about. They also have roughly 15 million in cap space with Zetterberg being placed on the LTIR and only RFA Dmytro Timashov to sign. Looking to further stock their prospect system, the right side of Detroit’s blueline is looking solid (Seider, Hronek) whereas the left side is looking pretty far off from being NHL ready (Johannsson, Wallinder).
That’s where defenseman Sebastian Aho comes in. An almost NHL-ready left-handed defenseman who is young and controllable. The Islanders can surely live without him as they have Leddy (UFA 2022), Pelech (RFA 2021), and Thomas Hickey (UFA 2022) under contract with the highly-touted Samuel Bolduc (RFA 2023) coming through the system.
With Boychuk’s contract off the books, the Islanders will have roughly $10,000,000 in cap space to sign Barzal, which should be close to enough for a long-term or bridge deal.
Islander fans may have a hard time coming to terms with what it takes to move a $6,000,000 36 year old in today’s COVID-ridden market, but in order to sign Barzal, this is the type of move that has to be made.
*Remember, Patrick Marleau was moved to Carolina for the last year of a $6.25 million contract for a 1st round pick before COVID-19 dried up markets around the league.

On the other hand, Detroit fans should be liking this trade. A veteran RHD who can be used in multiple roles on and off the ice including mentoring the young prospects coming up over the next couple of seasons though with limited minutes. They also acquire a young, controllable LHD with NHL-level talent and another 1st round and 3rd round pick to continue stocking their prospect system. In two years, the $6,000,000 cap comes off the books along with other larger contracts (Danny DeKeyser; $5million, Frans Nielsen; $5.25million, Thomas Greiss; $3.6million, Robby Fabbri; $2.95million, and Vladislav Namestikov; $2million). In 2022, Detroit will be able to target big market free agents assuming that they will be ready or close-to-ready to compete.

In Summary

New York Islanders
Free up $6million in cap space to sign Barzal
Open up room for their young defense core to get NHL playing experience

Detroit Red Wings
Gain a veteran presence on the blueline
Stock up on more prospects and picks for upcoming drafts
Utilize their cap space this season

I didn't need to read the paragraphs below.

This deal seems fine.

Value is fair and the idea seems plausible

I like it