I would need to see a 3rd really good acquisition to suggest that we could attempt some one on one's with the powers that be: Astros, Sox, Stros, Indians -- Dodgers, DC, etc
Lynn is one of the alts to the Darvish Otani double trouble dream match. But Lynn is a 114 ERA+ career and good for a 2.9 WAR average. This move alone gives you Pax-Lynn-Felix-Leake-Erasmo. Which to me is solid
With the money invested and time factor you have to get one of the decent 1B available. Yonder seems like a decent bet to perform well enough here 114 OPS+ down the stretch if you can pencil in a 110 to 120 OPS+ you can give the team a slight bump up vs the drag down from a bat 1st player in a bat 1st position completely flopping. 1.5 to 2 WAR well worth it vs a face plant.
So bumping Erasmo to the pen would be a spot for improvement I expect a decent year from Erasmo 1 to 2 WAR which is OK for a 5 but any of the available FA's should improve on those odds and range of pssible outcomes. Darvish, Otani, Cobb, Arrieta
OF either a corner or CF I like Cain bacause a soft WAR player athletic CF types seem to age better like Tori Hunter. I also think Cain can be had for 4-5 16 to 18 M per.
3 improvements I say 50-50 get me my requested 4 ( Darvish, Otani, Cain, Yonder) and I believe I'd favor the M's on the game consol or paper.