Remind me why Yankees shouldn't sign free agent J.D. Martinez.

J.D. Martinez will probably be the biggest free agent bat available between the 2017 and 2018 seasons. In the previous off season Yankee general manager Brian Cashman ignored the biggest bat, Edwin Encarnacion, and instead signed Matt Holliday. In the regular season Encarnacion out homered Holliday 2-1: 38 to 19. OPS+: Encarnacion 128, Holliday 95.

Supposedly one of the advantages was that Holliday was signed for only one year, which simply means that Cashman kicked the can down the road. Encarnacion signed with Cleveland for three years at a modest amount. Cleveland will be stuck with 38 homers for another couple of years. In his five previous seasons Encarnacion averaged 38 home runs.

Now the conventional wisdom in Yankee land is that the Yankees should run the other way if anyone even asks whether they should sign J.D. Martinez, because he will cost them hundreds of dollars and might threaten to play multiple seasons. A list of Yankee outfielders are mentioned as making his big bat unnecessary, including that of unproven Clint Frazier. What?

Oh, the rest of the argument is that the Yankees are finally close to getting under the team salary cap that Cashman crushed them into and perpetuated with signing Aroldis Chapman for $17 million for each of five years, 2017-2021. The idea is to pass on yet another big bat so that the Yankees can get under the cap for 2019 and then maybe, MAYBE, sign a REALLY expensive free agent. Maybe Bryce Harper for $40 million for each of ten seasons. Gee, that sounds a lot like the mess from which the Yankees are trying to extricate themselves. In about the same number of at bats, J.D. Martinez out homered Harper 45 to 29, with a higher OPS+.

Meanwhile, the Yankees could have traded for J.D. Martinez this season as a two month rental player. Arizona did. How did that work out?

July 18, 2017: Traded by the Detroit Tigers to the Arizona Diamondbacks for Sergio Alcantara (minors), Jose King (minors) and Dawel Lugo (minors).

Time will tell whether Alcantara, King, Lugo will make Arizona regret the trade. However, with Arizona J.D. Martinez hit 29 home runs in 232 at bats. Combined with his Detroit number: 45 homers in 432 at bats. His OPS+ for recent full seasons:
2014 154
2015 139
2016 142
2017 166

J.D. Martinez:
Bats: Right  •  Throws: Right
Born: August 21, 1987 (Age: 30 and 57 days)

So, come on. Remind me again. Why shouldn't the Yankees sign free agent J.D. Martinez?