I think it would be fair to say that the two biggest needs for the Bruins at the moment are solidifying their depth down the middle and strengthening the left side of the defense. There's a couple of key names that have already been thrown in the rumor mill and there's more options that will hit the market once certain bubble teams start to slip in the standings.
The usual suspects that are being talked about at the moment to back up Patrice Bergeron down the middle are Claude Giroux from the Philadelphia Flyers and J.T. Miller from the Vancouver Canucks. The cost to acquire Giroux would be far less than Miller since he doesn't have a deal in place for next year whereas Miller is signed for another year, at a reasonable cap hit of 5.25M$. Two other unrestricted free agents to consider would be Tomá� Hertl of the San Jose Sharks, who seems to be the big fish of this deadline but if Boston wants to be in the running, they'll have to take part in a bidding war to secure his services. The other option is Joe Pavelski, from the Dallas Stars, who is actually on pace for what would be a career year, at the tender age of 37. The only issue with Pavelski is that he's being utilized more so on the right wing than up the middle, but he's still a viable option nonetheless, considering the names we've seen pivot the 2nd line since the start of the season.
As for the left side of the blueline, the Bruins can use all the help they can get to find a stable partner for either Charlie McAvoy or Brandon Carlo. The ideal solution, which would also be a long term solution, would be someone who's been rumored to be on the block for weeks now and that's Jakob Chychrun of the Arizona Coyotes but the price tag will definitely take a huge bite out of the Bruins' future. Chychrun is already a top pairing defenseman who's 23 years old, is signed to a very affordable deal of 4.6M$ per which ends in the summer of 2024-25. If we're looking at more of a short term option, veteran Mark Giordano of the Seattle Kraken would bring some much needed poise and experience in the top #4. If ever the Anaheim Ducks start to see their playoffs chances diminish and they can't find a way to extend Hampus Lindholm, they will definitely consider moving him before the deadline. There's also names like Ben Chariot of the Montreal Canadiens and Ryan Graves of the New Jersey Devils but the impact they would have compared to the players before them would be marginal.
If Don Sweeney were to acquire any of the big name players listed above, he'll have to sacrifice some future but most importantly, figure out a way to not go over the salary cap, which in itself might turn out to be even more complicated than the negotiations.