Dunn and A.J. Ramos were sitting next to each other, and both were in the process of jumping and giving a fist pump because they knew the ball was gone.
"Then, I was like, 'This might come back,'" Dunn said. "I kind of glanced, and was like, 'Ahhh.' I went back and looked at the home run this morning. If I didn't move, I think it would have hit me. It would have been really close to hitting me if I didn't move."
Dunn estimates the back of the bullpen to the front is about 15-20 feet.
Stanton's immense power continues to impress the media, fans and those in the game.
"When he hits a home run and kind of gives it a step, that ball has a chance to leave ballparks, like out of everything," Dunn said.
On Wednesday night, Stanton's home run off Colorado's Jordan Lyles gained notice because of how hard it was hit to the opposite field. Not many right-handed hitters can drive a ball the other way like the 24-year-old.
Such shots could be dangerous in the Marlins' bullpen, because balls can ricochet off the back facing. To protect the video strip above the wall, they've installed a net lining. Dunn said balls spring off that strip like a trampoline.
Stanton has traditionally struggled in April, but he is off to a hot start.
Wednesday's homer was the earliest in a season of his career. Last year, he went without a blast until April 27, and he added two more on April 28.
In 2012, Stanton's first home run came on April 29. And in 2011, he connected for the first time on April 21.
If can learn to use all fields, like slugger Miguel Cabrera, Stanton could emerge as one of the most fear all-around hitters in the game.
"You look at Miggy, he's got all-field power," Marlins manager Mike Redmond said. "Giancarlo, if he can hit the ball the other way like that, wow. Not only would his batting average go up a lot, you'd be talking about the best hitter in baseball, if he can do that."
Along with belting an impressive home run, Stanton also reached a milestone on Wednesday. The slugger had three RBIs, giving him 300 in his career.