Manager Clint Hurdle cast the slow-starting shortstop in that light a couple of days ago in Los Angeles, proclaiming that "if we get Mercer swinging the bat, our lineup will be the best we've had here."
Agreeing with that assessment, Mercer said, "Well, yeah ... if we all get hot, there's no telling what we can do."
"We can hit the ball out of the park, we can run, we can do all kinds of good stuff," added Mercer, who pretty much did it all Monday night.
He notched his second-career four-hit game (Sept. 10, 2013 at Texas) to pump his average from .199 to .219. And he definitely ignited the lineup, into its biggest production in a month.
Its not as if the Pirates were lording over a weak pitching staff. The Padres may be going through a tough patch, but they brought into the game the National League's fourth-lowest team ERA (3.27).
"It's rare for this team to have games like this," San Diego manager Bud Black said afterward. "You don't see it very often, so when you do, it's rather alarming."
Yet, Hurdle reminded all that, before becoming a blowout, it was a 4-2 nail-biter heading into the seventh. He did so for two reasons: to commend Charlie Morton for pitching tough when he needed to, and his batters for their persistence.
The 16-hit attack spurred by Mercer and Josh Harrison, who had three hits of his own for his fourth multihit game since the Bucs arrived in California, moved the Pirates within three games of .500, the closest they have been to break-even since April 22 (9-12).
It also got the paradoxical Morton his second win of the season. Morton was literally unhittable and hung eight strikeouts through four innings -- then barely made it through the fifth.
"He was able to compete and get the outs he need to give us five solid," Hurdle said of Morton, who pitched out of the stretch a lot for a guy working on a no-hitter. "Even when he wasn't giving up hits, he dealt with a lot of baserunners."
Morton walked three, hit three others -- raising his Major League-leading total to 13 hit batters -- and even chipped in a throwing error.
By the end of the longest nine-inning home game in San Diego history at four hours, four minutes, all those glitches were buried under an avalanche of Pittsburgh hits.
"We just went up there, dug in and battled," Hurdle said of his batsmen, who made seven Padres pitchers labor through 249 pitches. "It's tight and close into the seventh ... we continued to go up there and grind out at-bats, to create a big separation. They were consistent and persistent in approach."
Mercer began the scoring with a solo homer in the third off Tim Stauffer, the reliever pressed into starting duty by the injuries that have ravaged Black's Padres rotation.
Mercer's blow provided a glimpse into the versatility of the Bucs' lineup. He was the seventh player to connect for the team's last seven homers, following Gaby Sanchez, Pedro Alvarez, Russell Martin, Ike Davis, Andrew McCutchen and Harrison.
Davis delivered another run in that third, lifting a sacrifice fly with the bases loaded for his 12th RBI in seven plate appearances in those situations. The total is tied for second in the Majors behind Cleveland's Michael Brantley, whose 16 have come in 12 plate appearances with the bases loaded.
In the fourth, Mercer singled to scored Starling Marte and make it 3-0.
After the Padres erased all but one run of that lead, Mercer was on the other end of a rally, singling off righty reliever Dale Thayer to start the sixth and eventually scoring on Neil Walker's single.
In the seventh, Mercer's single helped set up a three-run put-away rally that featured Walker's two-run double. In the eighth, Mercer walked ahead of Sanchez's two-run pinch-double.
"He's a good hitter," Hurdle said of Mercer, who'd set his personal bar quite high by hitting .285 in 103 games last season. "We felt he would come out of it. He just needed to get to a place where he wasn't over-thinking what they were going to throw him, just going up there and playing."
"It's something I had not been through before," Mercer said of the harrowing start to his season, and to his tenure as the Bucs' starting shortstop, that had him hitting .151 after 26 games. "But I'm going to be a way better player coming out of it. I had people who believe in me here, and having that support, you know it will turn around, and it did tonight."