Wow that feels a little heavy on McCutchen.
You might be right. I checked his FG WAR last year, and it was 2.6. If he duplicates that next year, and goes 2.1 and 1.6 the next two, it works out. If it were $36MM and I wouldn't bat an eye.
As the article linked below says, the contract looks somewhat similar to the Santana deal but no loss of draft pick, so effectively $15MM cheaper than Santana. Roster-wise, it gives them more options OF options when Hoskins moves to 1st and does not preclude playing in the Harper auction or otherwise blocking a second OF pick up.
https://www.fangraphs.com/blogs/andrew-mccutchen-boosts-a-lackluster-outfield/