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6/23/2014 11:12 P.M. ET

McGehee a big part of Stanton's offensive surge

No. 4 hitter taking advantage of opportunities behind NL home run leader

PHILADELPHIA -- Giancarlo Stanton is having a monster season: 20 home runs and 58 RBIs, and the schedule hasn't even reached the mathematical halfway point yet. He leads the National League in both categories.

Heck, he's only four homers and four RBIs short of matching his totals from last season.

Now, there are several interconnected reasons why the Marlins right fielder is tearing up opposing pitching. He's one of the most talented hitters in the game. He's in his fifth Major League season, even though he's still 24 years old. He's only missed one start after being limited to 116 games in 2013 by a serious hamstring injury.

But it's also impossible to overlook the impact of what has turned out to be one of the most underrated free-agent acquisitions of the offseason. A week before Christmas, the Marlins signed third baseman Casey McGehee for a guaranteed $1.1 million after he'd spent the previous season in Japan with the Rakuten Golden Eagles.

The Marlins weren't sure McGehee was the hitter they so desperately needed to give Stanton some protection in the lineup, either. They just knew that was an area they had to address. And the 31-year-old has contributed beyond anybody's wildest expectations.

The template for how it's worked was illustrated nicely in the first inning of the Marlins' 4-0 win over the Phillies at Citizens Bank Park on Monday night.

Stanton came to the plate against Phillies starter Roberto Hernandez with a runner on first and one out. Hernandez, working carefully, went to a 2-2 count and then came too far inside and hit Stanton with a pitch.

McGehee promptly doubled both runners home, giving him 46 RBIs for the season even though he has hit just one home run.

The lesson is that pitching around Stanton brings its own risk. The slugger has been intentionally walked 14 times this season. McGehee is batting .444 with six RBIs, two walks and a sacrifice fly following those walks. With runners in scoring position, he's hitting .395 (32-for-81).

"In getting Casey, we knew we had hole at third base and no one to fill it right now," Marlins general manager Dan Jennings said. "We used some contacts we had to look at what he'd done in Japan. And the two things that jumped out right away were that he had hired a nutritionist and that he had really geared his swing back toward the middle of the field. Gap to gap. Not turning and trying to pull everything.

"In doing the background check, we heard all these things about this guy in the clubhouse with his make-up and team-first mentality, it seemed like the perfect fit for what we needed and where we were."

Not that the Marlins anticipated this sort of production from a player who batted a combined .217 for the Pirates and Yankees in 2012. When he became a free agent that winter, his best offer came from Japan.

"Coming into Spring Training, we weren't sure who would be the guy to hit behind Stanton," Jennings continued. "[Manager Mike Redmond] tried some different things."

How well has it worked? Well, the Marlins were not only a distant last in MLB in runs scored with 513 last season, they were 85 behind the next team. They came into play Monday night ranked fourth in the National League in that category.

"[Adding McGehee] has had a huge impact," Redmond said. "We've talked about it a lot, about needing a guy to hit behind Stanton and give him some protection, or as much protection as he can possibly get. And he's done a great job."

Added Jennings: "Compared to last year and the record we had and where we were, what he's meant to this ballclub has been absolutely invaluable."

Now, the concept of protecting one of the game's most prolific hitters is a little misleading. McGehee is having a great season but, again, he has one home run. Stanton isn't going to start seeing fastballs down the middle because he's in the on deck circle.

Stanton is still the Marlins hitter that teams highlight in their scouting reports.

"In the pick-one-guy-in-the-lineup scenario that we talk about, he's the guy to watch," Phillies manager Ryne Sandberg explained. "Even if there are men on base and you have to pitch to him. He's the guy you don't want to let hurt you."

Still, having McGehee bat cleanup has clearly been a boost for the No. 3 hitter.

"The worst thing guys can do in this game is think they need to do it all themselves," Jennings said. "When you can pass the baton and know there's somebody behind you who can pick up the slack, it allows you to be more selective and do a better job on hittable pitches. And that's been the case with those two guys for sure."

Said Stanton: "It all goes back to the same thing, that you have to wait for your pitch. There are still going to be times even with people behind you that they're not going to pitch to you. So I don't really like that excuse that much. But it's a lot more comfortable having somebody behind you.

"His presence there every day, each at-bat is a solid approach. So you know you're going to get a solid at-bat. He's not going to chase too many pitches. He's going to be a tough out every time. To have that behind me every single day is definitely a plus in helping us anchor the lineup."

Stanton is having a superb season. There are numerous reasons why. And McGehee is near the top of the list.

Paul Hagen is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.