Bruins won't include a top4 defenseman in a trade bringing back another top4 D. They're back to square one.

This goes to show you don't know the Bruins, we wouldn't trade for Tarasenko unless we desperately needed a top 6 forward, and Craig smith is no use on the 3rd line. Also there is no way Boston is trading Matt Gryzelcyk, our 2nd best defenseman who is likely gonna average at least .7 points per game for a guy who wont even be a top 4 defenseman according to you. Our defense is deep and solid, please stop with these cancerous Bruins armchair GMS until you watch a whole season of Bruins hockey.

Good Tarasenko trade but the blues wont retain

Boston doesn’t desperately need a top 6? They were one of the worst 5v5 scoring teams in the league. Craig smith useless on the third line? That’s where he played most of the season, second line was JD, Krejci and Ritchie. When Smith played with Frederic and Coyle, they had really good chemistry. Gryzelyck was a huge liability in the playoffs and even at times during the season. He even lost his spot on the first power play to McAvoy. Ekholm is not only just an overall better player than Gryz but will also play on the third pairing because of the fact that Martinez is being signed. The Bruins d was not deep and/or solid. It showed when Carlo got injured that there are holes and gaps that need to be filled.

If it takes a sweetener to get them to retain, the bruins have the assets to do it.

Ekholm > Gryz, bruins upgrade
Nashville gets rid of an expiring deal of a player they’ve been shopping, for a decent haul.

Why would the Bruins trade for a one year rental over a younger defenseman who has three more years on his contract (at a better price)?

Bruins want to add another top4. Grzelcyk isn't going anywhere.