So many similar hitters have fallen off big at this age:
Jayson Werth at 36
Adrian Beltre at 36
Victor Martinez at 36
Mattt Holliday's power is on a 3-year decline and he's 35
In terms of recent hitters who remained good investments at close to 40, you're looking at David Ortiz. Letting both walk and collecting the compensation picks and salary flexibility while letting someone else gamble 15-20M/year on a couple of guys in their mid-late 30s is a pretty viable plan.