Could the Diamondbacks Sign J.D. Martinez to be their DH?

Martinez has seen a noticeable decline in his power numbers since leaving Arizona after the 2017 season.

Five years ago the Diamondbacks were able to trade for J.D. Martinez, who provided a boost in the lineup necessary for them to finish with the top Wild Card slot and a National League Division Series appearance. He hit 29 home runs in 62 games with Arizona, just in time for free agency. They weren't able to re-sign him in the off-season, as Martinez signed a five-year deal with the Boston Red Sox. Now he's back on the free agent market, albeit in a much different situation than five years ago.

Martinez is coming off a down year, in which he hit .274/.341/.448 with 16 home runs and 62 RBI with Boston. The 16 home runs is the lowest total for him in a season in which he had at least 500 plate appearances since 2016. In addition to the drop in home runs, the batted ball data shows a very concerning decline. His exit velocity dropped 3 MPH from 92.1 to 89.1 and his Statcast hard hit rate, which accounts for exit velocities greater than 95 MPH, dropped from 49.4% to 41.7%. By both metrics, his ability to impact the ball has diminished. 

As the case with Evan Longoria, Martinez brings both a veteran presence and a still capable bat at the right price. He was still an above-average hitter, as Fangraphs graded his offense as 19% better than the average major league hitter with a wRC+ of 119. He also hit 40 doubles in back to back seasons, so he's still making impactful contact and racking up extra base hits. With the reduction in exit velocity and hard hit rate, it's turning what were home runs in the past into doubles. 

In Arizona, Martinez would likely be the D-backs clean-up hitter and likely batting between Ketel Marte and Christian Walker. He also adds some solid right-handed power to the middle of the lineup to balance out a lineup that's become very left-handed the past couple seasons. In Arizona, Martinez' best case scenario is he starts 130-140 games at the designated hitter spot as a .260 hitter with 20-25 home runs. On the flip side, it's possible that he's close to physically done and the D-backs should be very cautious about signing him. 

Martinez is a nice player to have, at the right price. At 35, coming off just a 1.0 WAR season that price may be closer to the ballpark of $10 million on a one-year deal. The D-backs should wait out the market and see if Martinez's price comes down, as there's no reason to jump if the asking price isn't quite right.