2. Pete Alonso to the Yankees
This one would sting, and Mets fans (myself included) would never forgive him for it, but the truth of the matter is that the Yankees could really use a guy like Pete Alonso. Ben Rice had a great year, but Alonso is a clear upgrade; this could be the move that gets the Yankees over the hump next year.
Following the last game of the regular season, Alonso immediately opted out of his 2-year, $54 million contract with the Mets, and rightfully so; he is coming off arguably the best year of his career, slashing .272/.347/.524 with 38 home runs and 126 RBI. He is going to make a lot more money this offseason and he knows it, which is why all options are on the table, including a crosstown trip to the Bronx.
Where the Yankees might find trouble in Alonso is his fielding and baserunning; he's been bottom of the barrel in those regards since the start of his career, but they should be able to look past that for how prolific a power hitter he is. I would guess (and hope) that Steve Cohen will reach into his pockets to bring Alonso back home, but don't be surprised if he's playing for the other New York team come the spring.