BOSTON -- As you might have heard, David Ortiz is setting a new standard for 40-year-old baseball players everywhere with his 42 doubles, 31 home runs, 74 extra-base hits, .318 average and 1.039 OPS. Few sluggers in their fifth decade of life have ever put up such eye-popping numbers in every major offensive category.

But while Ortiz raises the bar on what it means to be 40 in the big leagues, Mookie Betts is doing the same for fresh-faced 23-year-olds.

Ortiz and Betts, the Boston Red Sox's dual MVP candidates, represent opposite ends of the career spectrum. Despite his overwhelming success, Ortiz plans to retire at season's end, his feet and heels aching too much to compel him to come back for one more year. Betts, meanwhile, is only just getting started, a terrifying thought for American League pitchers.

On Monday night, Betts fueled another Red Sox victory -- 9-4 over the Tampa Bay Rays at Fenway Park -- with his 30th home run of the season, a leadoff missile in the second inning off right-hander Matt Andriese that practically dented a sign above the Green Monster in left field. He added an RBI double into the left-field corner in the fifth inning for his 96th RBI and scored his 102nd run two batters later on Travis Shaw's infield single.

And when Betts stepped to the plate in the seventh inning, he was greeted by chants of "M-V-P," an acknowledgment of all he has meant to the Red Sox all season long and particularly since the All-Star break.

"It's cool to be a part of that, but I've got to know that what we're doing, we're in a [pennant] race right now, and I think that's the way we want to focus," Betts said before slinging a backpack on his shoulders like the college students who will be returning to Boston en masse next week. "It's pretty cool, but there's guys around the league that are doing more than I am."

Good luck finding them. Houston Astros second baseman Jose Altuve, Toronto Blue Jays third baseman Josh Donaldson and Los Angeles Angels center fielder Mike Trout figure to be Betts' chief competition for MVP, each making his own compelling case. But in only his second full big league season, Betts is exceeding even the Red Sox's wildest expectations.

Betts, an eighth-round draft pick in 2011, has always possessed lightning-quick hands and an uncanny ability to recognize pitches in the strike zone. But he never hit more than 15 homers in a season in the minor leagues, which leads him to say he "wasn't expecting the power like this."

Neither was Red Sox manager John Farrell, who three weeks ago could no longer resist the urge to move such a prolific run producer from the top of the order to the cleanup spot.

"What he's doing in the second half now is well above I think maybe what we expected coming into the second half of the season," Farrell said. "There's no sign of fading in Mookie. He's responded extremely well to the 4-hole. Mookie, at his age, for what he's producing, it's not only strong, but it's very rare."

Indeed, Betts became only the third Red Sox player ever to hit 30 homers in a season before his 24th birthday, according to the Elias Sports Bureau. Ted Williams hit 31 in 1939 at age 20 and 37 in 1941 at 22, while Tony Conigliaro hit 32 as a 20-year-old in 1965. Betts also is only the fourth Red Sox player with at least 30 homers and 20 stolen bases in a season, joining Carl Yastrzemski (1970), Nomar Garciaparra (1997) and Jacoby Ellsbury (2011).

It's plain to see, then, that Betts' season is one for the ages. Just don't tell him that.

"Yeah, it's unbelievable," said Red Sox starter Rick Porcello, who gave up three runs in seven innings to become the majors' first 18-game winner and only the fifth pitcher ever to begin a season 13-0 at home. "I said, 'Congratulations on 30 home runs,' and he goes, 'Thanks. I'm just doing what I can.'

"You look at his talent level and what he's accomplished already at this young of an age. I think for me, getting to know him on a personal level and playing with him every day, it's even better that he's such a great kid and he's a good teammate. It's an honor playing with him."

Years from now, Porcello surely will reminisce about what it was like to see Ortiz defy the aging process in the most successful farewell season in history.

By then, who knows how good Betts will be or where his potential will take him when he's actually in his mid-20s? Or in his early-30s? Or 40, like Ortiz?

"I don't really know," Betts said. "I don't know how to analyze those things. I just try to be the same guy each and every day and just do something when we're hitting or make a nice defensive play or run the bases. Just trying to be consistent in that way."

Betts is also raising the bar for the next young Red Sox star who comes along.

As Ortiz can attest, that's what great hitters do.