It's only May, but when Dodgers center fielder Matt Kemp steps up to the plate at Chavez Ravine, he's greeted by an August-level MVP serenade.

When Kemp's teammate Andre Ethier leaves the on-deck circle, there are times those same "MVP" chants ring -- but it's simply an extension of Kemp's at-bat and not in support of the Dodgers right fielder, who is leading the National League with 30 RBIs.

Ethier's presence has been especially vital to the Dodgers' hot start. The success he has had represents a bigger trend early this season: superstars like Kemp playing their parts, but perhaps taking away a bit of recognition from their teammates who are also off to solid starts.

In Washington, there's a Gio Gonzalez for much-hyped ace Stephen Strasburg. In Philadelphia, there's a Vance Worley for the big three of Roy Halladay, Cole Hamels and Cliff Lee. In Boston, there's a Ryan Sweeney for seven-time All-Star David Ortiz.

"If it wasn't for Matt, we'd be talking about Andre," Dodgers manager Don Mattingly said. "Every run Matt doesn't drive in, Andre does. Matt and Andre are like Batman and Robin."

Players like Gonzalez and Sweeney may be painted as the Robin to their teammates' Batman, but they've been worth much more to their clubs than being a sidekick.

It was in Los Angeles two weekends ago when the spotlight was on the Nationals as rookie Bryce Harper made his Major League debut with Strasburg on the mound. Strasburg has been dominant for the Nats this season, allowing just seven runs in his six starts, for a 1.66 ERA and a 2-0 record.

Strasburg has been garnering praise for his start to the season, and given the numbers, it's easy to see why. But when Gonzalez, who was acquired from Oakland in the offseason, took the mound the next day, there wasn't nearly as much fanfare.

No matter, Gonzalez simply extended his scoreless-innings streak to a club-record 25 1/3 innings. He, too, has started six games and allowed just seven runs. He has been just as vital as Strasburg to a Nats squad that has assumed first place in the National League East thanks mainly to pitching.

It isn't exactly in Gonzalez's personality to mind flying under the radar. After his first win, his response was to thank the Nationals for their decision to bring him to Washington.

"It's almost like a thank you from [general manager Mike] Rizzo [and] the Lerner family for taking a chance on me," Gonzalez said in mid-April. "So little by little, I'm going to try my best to continue to give them what they want. It's all smiles from there, especially with the new rotation. I don't want to be left behind."

If he keeps up his hot start to the season (3-1, 1.72 ERA, 41 strikeouts in 36 2/3 innings), it's safe to say he won't be.

As for Worley, he's in a similar situation. Two-time Cy Young winner Halladay was his usual self to start the season before losing his past two starts, and the club's two All-Star lefties, Hamels and Lee, have pitched well, too, though Lee ended up on the disabled list after his third outing.

Yet it's the unheralded Worley whose 2.84 ERA -- even after a shaky outing against Washington -- fits right in with Halladay (3.28), Lee (1.96) and Hamels (2.45).

In Boston, Ortiz's April was reminiscent of his seasons from the mid-2000s, as he drove in and created offense for a Boston club that got out of the gate slow. Meanwhile, Sweeney, a quiet offseason signing, is right up there with Ortiz among the team leaders.

With four hits Sunday, Sweeney overtook Ortiz by three percentage points for the team lead in batting average at .368. He's since dipped behind Ortiz but he's still batting .360, leads the American League with 13 doubles and is second on the Red Sox with a .389 on-base percentage.

Nowhere has a top two been as noticeable as in Los Angeles, however. Kemp has made headlines for his hot start, while much of the talk about Ethier has revolved around his impending free agency and if the club's new ownership will make re-signing him a top priority.

"He's had a great start," general manager Ned Colletti said last month. "Except for a little bit of a blip when he had a bad knee last year, he's been a very consistent player for us and somebody who does provide some protection for Matt. He's somebody that we count on and somebody that's been here really his whole Major League career."

Ethier's RBI pace has been the biggest challenge to Kemp's early Triple Crown charge. He is hitting .277 with six homers -- all while providing vital protection for Kemp's bat in an otherwise pedestrian Dodgers lineup.

Ethier is an early All-Star candidate. He's a reigning Gold Glove winner and career .291 hitter. But sometimes, when playing alongside an all-everything player like Kemp, those feats go a bit unnoticed.

Ethier's not the only overshadowed ballplayer, these days. And while it's Batman who inevitably takes all the glory, it may be the sidekicks who hold the keys to their teams' success.