3) NY Mets should demand Cubs prospect Ben Brown
Ben Brown's name appeared on the radar for the first time when he was the prospect traded for David Robertson at the trade deadline. This upset Mets fans as Brown was ranked towards the bottom of the Cubs top-30 list according to MLB Pipeline and New York didn't top that at the deadline last season.
The Phillies wound up snagging Robertson, but Brown has turned out to be the real prize of the deal. The right-hander might've been a 33rd round pick in the 2017 draft but he's turned into one of the best prospects in the majors. He's the fourth-ranked Cubs prospect and 86-ranked prospect on MLB Pipeline overall.
Brown got off to a blistering start in his first four AA starts but struggled after being promoted to AAA to the tune of a 5.33 ERA in 22 appearances (15 starts). While struggles are never fun, the 24-year-old displayed some electric stuff with 100 strikeouts in 72.2 AAA innings pitched. His walks were high, but he presumably should be able to improve that with more experience.
Brown isn't quite the centerpiece in a deal like this, the Mets would really need at least one of Crow-Armstrong or Horton, but he'd be an awesome secondary piece in an Alonso trade and can really help round out the future Mets rotation.