"Just up there looking for his fastball," Martinez said of his approach vs. Gray. "Trying to react to anything else is kind of what my approach has been off him. Just got a fastball down and put a good swing on it."
Martinez now has 24 homers since the All-Star break (22 with the D-backs), trailing Marlins slugger Giancarlo Stanton by just four in that span. Only Stanton (54), Aaron Judge (41) and Khris Davis (39) have more homers than Martinez's 38 this season.
"Offensively, what can you say about J.D.?" Arizona manager Torey Lovullo said. "He's been very consistent. He's doing his job every single night at the right moment. I think he tied a career high with his 38th home run today. So he continues to be a huge offensive force in the middle of our lineup."
Martinez's homer traveled 447 feet and with an exit velocity of 113.7 mph, according to Statcast™, making it the D-backs' hardest-hit homer this season. Prior to that, the club's hardest-hit homer was a 112.8-mph shot by Martinez during Arizona's 3-2 win over the Padres on Sunday.
"He's really hot right now," Gray said. "He's swinging the bat right now. I'm just fortunate it was a solo shot. I knew I had to lock it in from there and move on."
Martinez wasn't the first D-backs player to clank a ball off the scoreboard this season; Paul Goldschmidt smashed a 453-foot shot off the big screen on May 14.
"I didn't even know where it went," Martinez said. "I just hit it and ran."
Jarrid Denney is a reporter for MLB.com based in Phoenix. This story was not subject to the approval of Major League Baseball or its clubs.