Changing my choice: the 2nd baseman will be Bogaerts... after the Sox trade for Francisco Lindor. If the argument against that idea is that shortstop is not an area of need, here's the counter: on a last place team, really good players are an area of need. This is the splash to put this franchise back in the spotlight.
Boston needs pitching, and free agent pitchers certainly consider a team's defense and a club's chances at winning when mulling offers. The Sox need better players in a lot of places to contend, and adding a new face of the franchise will show peers and fans alike they're serious (plus, keep a guy like Lindor from joining rivals).
Lindor will thrive under Cora, the Sox will extend him with some of the Mookie money (7 for 210), and invest the remaining hundred mil on starting pitchers and relievers... They can still afford a platoon centerfielder like Marisnick, and re-sign Moreland to share first with Chavis, while awaiting the debuts of Duran/Jimenez and Casas.
Cleveland reportedly wants a Betts-like return for Lindor, so the first to go in the deal would be Downs, and next would be Dalbec. The trade simulator approved this swap... but only after the Tribe also kicked in Carlos Carrasco, also rumored to be on the block. The block between Lansdowne Street and Renamed Street would welcome him, too.