Gentry suffered a lower back strain nearly three weeks ago, and there's no timetable for him to get in a game. Fuld, in the meantime, has been stellar on defense and impressive at the plate, too, going 7-for-22 (.318) with a home run in nine games.
Like Gentry, he can play all outfield positions and is accustomed to a part-time role. He's a .234 career hitter in parts of six seasons with the Cubs and Rays.
"I knew he was a good player. I didn't realize he was this good," said Melvin. "Gentry's been out, and Sam's been a guy that can play any of the outfield positions plus-plus. There were two balls yesterday I didn't think he was going to get to, and he got to easily.
"Usually there's a falloff at different positions. There's one you're most comfortable in, and then a little falloff. There's no falloff with him."
Fuld came to the A's on a Minor League deal worth $800,000 if he makes Oakland's roster. It includes $100,000 in incentives for games played and, more importantly, a pair of opt-out dates if he's not on the big league roster. The first is at the end of this month. The second is on June 1.
"At the beginning of the season, there are guys you want to keep and not let get away," said Melvin. "If we're able to do that, I don't know, but we're mindful of it, and there's a reason they're here. You don't just bring guys in that are out of options or have outs just to have them there for Spring Training."
Jane Lee is a reporter for MLB.com. Read her blog, Major Lee-ague, and follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.