Leave it to Manny Ramirez to make the case that there is no difference between facing a rookie starting pitcher and a veteran.

"It really doesn't matter. It's the same," the slugger said with a shrug and a smile this week while his Los Angeles Dodgers were in town to face the Washington Nationals' rookie-laden rotation. "They've got to throw it over the plate _ and you've got to swing."

Certainly true. And so is this: Young hurlers are appearing in modern-era-record numbers this season.

With 10 days left in the regular season, there already have been more starts by rookie pitchers in the majors in 2009 than in any year since the 1800s, according to STATS, and the consensus seems to be it's part of a general trend of relying on youth, in part because of the cost savings.

"I guess I'm not surprised," Nationals president Stan Kasten said. "There's clearly been more of an emphasis on rookie development in recent years, a move away from older players and going to higher-ceiling, more-affordable players that you've developed through your own system. People are seeing _ or believing _ that that's increasingly a better way to build."

There were 918 starts by rookies entering Friday; no other post-1900 season had more than the 900 in 2002, STATS said.

Some of the kids have been superb: Detroit's Rick Porcello (14-9, 4.14 ERA) and Philadelphia's J.A. Happ (11-4, 2.79 ERA) even could play key roles in the postseason.

Porcello was among the 11 rookies who started games around the majors on Wednesday alone, and they went a combined 6-3 with a 4.35 ERA, 33 strikeouts and 20 walks.

Not too shabby.

"It just depends on the individual," said New York Yankees lefty CC Sabathia, part of an all-veteran rotation. "You're going to have some struggles, definitely, your rookie year; have some ups and downs. You know, you're going to be all over the place. But if you've got the right guys around, you know, you can easily have a successful year."

Porcello is clearly special, the youngest pitcher to win 14 games since Dwight Gooden burst onto the scene with the New York Mets in the 1980s.

"He's my favorite pitcher," said Porcello's teammate, Carlos Guillen. "He's not afraid of anybody. He's 20 years old and goes out there and says, 'Here's my fastball, see if you can hit it.' Most guys can't."

Most rookies, though, have not had that sort of success _ no matter what Ramirez may claim about there being little to separate oldies from newbies.

Rookie starters have a .461 winning percentage and 4.92 ERA this season, while non-rookies are at .509 and 4.34, according to STATS.

Plus, rookie starters go 5 1-3 innings per outing; others average six innings.

"We've had to have patience as the year's gone along and take it on faith that they'd learn from the experience and we'd be better for it," Oakland assistant general manager David Forst said. "We're happy with what all of those guys, to a man, have gotten out of their first year in the big leagues."

His A's leads the majors with 110 games started by rookie pitchers.

Trevor Cahill (10-12, 4.45 ERA) made 31 of those, and Brett Anderson (11-10, 4.12 ERA, rookies-leading 145 strikeouts) made 29. Anderson won his fourth consecutive start Thursday; he tossed a two-hit shutout of Boston in July.

Forst did caution: "Their development certainly is not complete just because they have time in the big leagues."

Like Oakland, the Baltimore Orioles (91 rookie starts) and Kasten's Nationals (an NL-high 89) are hoping whatever rough patches came this season will pay off eventually.

"It has been a season of opportunity," Orioles manager Dave Trembley said, "and the benefits and rewards will come down the road."

Perhaps. There are no guarantees, of course.

The Nationals have trotted out rookies Jordan Zimmermann, Craig Stammen, Shairon Martis, Garrett Mock, J.D. Martin, Ross Detwiler and Marco Estrada this season, and the team has had four of those youngsters in the rotation simultaneously.

That group is 20-33 for a .377 winning percentage _ which is not very good, certainly, although it looks a lot better when you consider the team's overall winning percentage is under .350.

Washington is hoping to turn things around with the help of yet another up-and-comer, hard-throwing right-hander Stephen Strasburg, who signed a $15.1 million contract after being the No. 1 overall pick in June's amateur draft.

"With the economic situation that we're in right now, teams are going with cheaper alternatives and they're trying to develop from within. I don't think that's a bad thing," Washington catcher Josh Bard said. "Business-wise it seems like a good move, but they're going to have to be patient, because it's tough."

In other words: It probably is no coincidence that the Nationals have lost 100 games and own the worst record in baseball.

Or that the A's and Orioles are last-place teams, too.

Or that Sabathia's playoff-bound Yankees (only one start by a rookie pitcher this season), Boston Red Sox (four), Dodgers (seven) and St. Louis Cardinals (10) are at the opposite end of the list.

"In Washington's case, they're trying to get some information now so they can paint a picture for themselves. I mean, I've been there, and it's certainly important to see what you have, see how a pitcher reacts to challenges and stuff," Dodgers manager Joe Torre said.

"The only way you can play this game is to be able to pitch. So even if a youngster may be having his first start or his first couple of starts, it's still important to take away from it an idea of where you're going," Torre said.

Zimmermann looked the most promising of Washington's crop, going 3-5 with a 4.63 ERA and 92 strikeouts in 91 1-3 innings, until needing reconstructive elbow surgery that is expected to sideline him for most _ if not all _ of 2010.

Ask Zimmermann what the toughest adjustment is for a rookie starter, and you hear pretty much the same thing if you ask a Cahill or a Porcello.

"You've got to mix up your pitches and work down in the zone. If you work up in the zone, you're going to get beat up pretty hard up here. I just had a couple mistakes every game that cost me a couple runs here and there. ... Stupid mistakes," Zimmermann said. "In the minor leagues, if I make those mistakes, the guys usually swing and miss or foul them off or something. But up here, if you make the mistake, they're going to get you."

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AP Baseball Writer Ronald Blum in New York, AP Sports Writers Janie McCauley in Oakland and David Ginsburg in Baltimore, and AP freelance writer Chuck Murr in Cleveland contributed to this report.