Gray drilled a 1-0 pitch from Cincinnati Reds starter Scott Feldman into the center-field seats in the bottom of the second inning at Coors Field in Denver on Wednesday; the ball traveled 467 feet, marking the longest home run by a pitcher since since MLB's Statcast began tracking distances in 2015.
According to Statcast, Gray's two-run blast also was the longest Rockies home run of 2017.
"I see Jon in [batting practice], and he has some strength to his swing," Rockies manager Bud Black said after his team's 5-3 win. "That ball was crushed."
Too bad Gray won't ever get it back as a souvenir. The ball landed in the stands and bounced into the pond behind center field, joining a bevy of baseballs from batting practice.
"It's gone. Forever," Gray lamented.
At least he has the memories -- and the accolades from teammates, who were awed by his mighty swing.
"They really didn't say much, just, 'Man, that was crushed,'" Gray said. "I told them the same thing: 'It felt good.' I tried to put a good swing on it."
Gray even did a little skip after contact and rounded the bases at a leisurely pace.
Gray also was solid on the mound, going 5⅔ innings and allowing three runs, two earned, in his second start since a broken bone in his left foot sidelined him for two months.
"It wasn't a good day on the hill," Gray said of his performance. "I didn't have a feel for anything, really."
Rockies shortstop Pat Valaika would debate that.
"It's good to have high standards. But I think if a pitcher keeps us in the game, he had a good game," Valaika said.
Entering Wednesday, Gray, 25, had seven career hits -- all of which came last season -- in 55 plate appearances.
Gray has surrendered 24 home runs in his three-year major league career; none has traveled farther than 455 feet (Ryan Howard on Aug. 12, 2016).
The Reds have allowed two pitchers to hit home runs this season, both Rockies pitchers. Left-hander Kyle Freeland went deep at Great American Ball Park on May 21.
Feldman said he regretted that pitch to Gray.
"I feel like you should get the pitcher out every time," Feldman said. "So, to pretty much lose the game on that, not a good feeling."
Information from ESPN Stats & Information and The Associated Press was used in this report.