Moss and Reddick, who both previously played for the Red Sox, are in town for the start of a three-game series Monday night against the Red Sox.
They spent time at Boston's Children's Hospital, visiting Aaron Hern, who is from the Oakland area, and had his left leg hit by shrapnel in the bombings.
"It was awesome," Reddick said after a 9-6 loss to the Red Sox. "Just to meet a family from the California area who had been through just as much as this whole city has, and to just brighten up their day and kind of get their minds off of what happened the whole week and forget where they're at for a few hours. It was big.
"And you could see the kid's face light up, and even the parent's faces light up. For us to be able to get them out of that hospital scene for a while, it was a good sign."
Oakland manager Bob Melvin talked about how the two players were glad they went and were emotional from the visit.
"I (spoke) with Mossie a little bit," Melvin said in the dugout, while the players were stretching prior to the game.
"He said that he was very glad and it was a very touching moment, and that the perspective that you get when you're there talking to someone that's been involved - as opposed to coming out here and losing a baseball game, it's pretty insignificant - they were glad to do it and they're probably better for it, too."
Melvin also discussed how it was when the team was making its way to the hotel Sunday night.
"It was a pretty eerie feeling last night driving up," Melvin said. "You look down Boylston Street and it's still closed, with all the TV trucks and satellite trucks still in the area. You can only imagine what it was like at that time.
"That's the great thing about baseball and sports, we're able to provide some entertainment for two, three hours, whatever it is."
Reddick was also touched driving near the scene before getting up in the morning with their planned visit.
"We drove in by it last night from the airport, past the memorial service, so that was kind of a heart-sinking moment," he said. "But I think we've both been in that hospital before, so we know what kind of stuff that hospital has to offer. We had just as much of a blast as that little kid and his family did, so it was good for us, too, to put a big smile on our face."