Now that the Yankees have bid farewell to that gloried but antiquated relic they have called a home since 1923, it’s time to figure out when they’re going to start hoisting new pennant and championship flags at their McMansion across the street. In other places, I have advanced the notion that the Yankees will celebrate the 10th anniversary of the 2000 World Series winners before they have a new championship to celebrate. This has provoked a rejoinder from the diehards in the audience that goes something like this:

“Aw, you know the Yankees will be back faster than that. They’ll spend the money to make it happen. Besides, the Orioles and Blue Jays will never get it together, and the Rays are just a flash in the pan. That makes the Red Sox the competition, and their core is starting to age. Look at Jason Varitek! They’ll have to rebuild soon, which means the Yankees will float back to the top like the croutons in your split-pea soup.”

Yes, look at Varitek, because his is the only position where the Red Sox don’t have a solid plan B waiting in the wings. The problem with this theory as it pertains to the Red Sox is that they’re already rebuilding, and they’re far more committed to the idea of doing it with young players than the Yankees have been at any time since the 1950s. Prior to the season, Baseball America and Baseball Prospectus came to identical conclusions as to the top 10 prospects in the Red Sox organization, though differing on the exact order of ranking. Of these, the closest to the majors were pitchers Clay Buchholz, Justin Masterson, and Michael Bowden; outfielder Jacoby Ellsbury, who had already made a splash in the fall of 2007, and shortstop Jed Lowrie. Every one of these got at least a cameo with the big league club, with Ellsbury, Lowrie, and Masterson moving into key roles. Buchholz struggled with his mechanics and had to be sent down for remedial work, but at 24 he remains a promising prospect.

In acquiring Jason Bay and dealing away Manny Ramirez, the Red Sox went from a 36-year-old to a 29-year-old in left field. Lowrie, who should take over for Julio Lugo at shortstop next season, is 24, as is the inconsistent Ellsbury. Second baseman Dustin Pedroia, who may well win the American League Most Valuable Player award, is 24. On the pitching side, Jon Lester has established himself as at least a number-two starter at 24. Masterson, who pitched well both as a starter and a reliever, is 23. Bowden, who has only had one start so far, is just 21 and posted an ERA of 2.62 in a season split between Double- and Triple-A. Perhaps most intriguingly for a team that is always just a bit short in the bullpen, 2006 first-round pick Daniel Bard, who looked like a bust a year ago, moved to the bullpen and dominated with his fastball at Double-A. In other words, Mike Timlin, here’s your gold watch.

Further down in the system, 21-year-old outfielder Josh Reddick hit.311 AVG/.356 OBA/.544 SLG across three levels before finishing at Double-A. Reddick has good defensive abilities, so the Sox may be able to challenge Ellsbury and Coco Crisp with a power-hitting alternative by 2010 at latest. First baseman Lars Anderson, who turns 21 in just a few days, hit .317/.417/.517, finishing strongly at Double-A. He and Kevin Youkilis may soon finish the process, begun by injuries, of making Mike Lowell a part-time player.

Contrast this with a Yankees system that has begun to deliver pitchers — and you have to put a big asterisk on that statement because the Yankees won’t enter 2009 with any more established young pitching than they had at the outset of 2008, with even Joba Chamberlain consigned to middle relief again — and has just two upper-level players of any real interest: Brett Gardner, who will have to prove he’s not a fourth outfielder with great tools and no bat, and center fielder Austin Jackson. It’s a long way down to Low-A and catcher Jesus Montero, a hefty slugger whose probable future role is that of a full-time DH, the Yankees’ answer to David Ortiz, the Pinstriped Papi.

Nor will things be getting better in the near future. The Red Sox signed their first 14 draft selections this year. The Yankees, who intentionally picked an injured pitcher with their first-round selection in 2007, were flatly turned down by their first overall pick this year and decided they weren’t interested in their second-round pick. That meant that first-round supplemental pick Jeremy Bleich, a lefty with no great stuff and injury problems of his own, becomes the team’s standard-bearer for this draft, which shows all the signs of being a historic bust. No, the question isn’t when the Red Sox have to rebuild, it’s when the Yankees will finally start.

Mr. Goldman writes the Pinstriped Bible for yesnetwork.com and is the author of “Forging Genius,” a biography of Casey Stengel.