The New York Yankees just did something they hadn't done in 27 years: They became sellers ahead of the trade deadline. Their best bet for long-term success is to keep going.

On Monday, the Yanks dealt closer Aroldis Chapman to the Cubs in exchange for top shortstop prospect Gleyber Torres, outfield prospect Billy McKinney, swingman Adam Warren and Class A outfielder Rashad Crawford.

In Torres, New York landed a player named the No. 27 prospect in baseball this spring by Baseball America. McKinney is coming off a major knee injury and was slugging just .322 in Double-A at the time of the trade, but he's also a former first-round pick. And while Warren won't win any Cy Young awards, he's a useful right-hander who can start and throw effective relief innings. Warren is returning to his former team after the Yankees sent him to Chicago as part of last winter's Starlin Castro trade.

All told, the Yankees essentially traded fringe prospects Caleb Cotham, Rookie Davis, Tony Renda and Eric Jagielo for Castro, Torres, McKinney, and more. That's a great haul for a pitcher who's set to test free agency at the end of this season and a harsh indictment of the Reds' haul in the initial Chapman trade.

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The Chapman trade could signal a philosophical shift in New York. USATSI

It's also a curious pivot on a player whose market value plunged when he was accused of choking his girlfriend and firing eight gunshots to terrorize her, only to see his value fully and oddly return just a few months later, after Chapman admitted to firing the shots (but without criminal charges being filed against him).

But the bigger story is what the trade says about the state of the franchise. The Yankees haven't had a losing season -- or even a year with a winning percentage as low as the current .515 -- since 1992. Even with just one World Series win in the past 15 years, that's still one of the greatest runs by any North American sports franchise in a long time.

Now, with mediocrity setting in, they've become deadline sellers for the first time since 1989, when they traded away 30-year-old Rickey Henderson and fading veteran third baseman Mike Pagliarulo. (As CBS Sports colleague Mike Axisa notes, the Yankees did trade Gary Sheffield for three prospects a few years ago, but that was because they added Bobby Abreu at the trade deadline and had two right fielders.)

The Yankees' long-standing mantra (sometimes spoken, sometimes unspoken) was that their fans would never tolerate a rebuilding process. Trading away a reliever on the brink of free agency doesn't begin to approach a true rebuild. But with six days to go until the non-waiver deadline, the Yanks have a chance to snag a lot more valuable young talent, something they'll sorely need if they hope to contend with stronger AL East opponents in the years to come.

Go through the Yankees' major league roster and see if you can spot any players who truly deserve to be deemed untouchable. Start with the lineup, which includes just two players younger than 32.

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The Yankees have a lot of untradeable pieces on offense. USATSI

Alex Rodriguez and Mark Teixeira enjoyed terrific bounce-back seasons in 2015, but both look cooked this year, they won't be starters on the next winning Yankees team and offer no value to anyone. Chase Headley has needed a big recent hot streak just to hike his numbers back to within shouting distance of respectability, but at this stage he possesses neither the potent bat nor the slick glove that he showed near the end of his time with the Padres.

Brett Gardner is still a useful player as a speedy corner outfielder who can draw a walk, but he's also owed about $31 million through the end of 2018, making him an undesirable trade piece. The $21.1 million a year Jacoby Ellsbury is owed through 2020 (plus a $5 million buyout for 2021) makes him one of the 10 most untradeable players in baseball.

On the pitching side, CC Sabathia might be unmovable, since his $25 million option automatically kicks in this season unless he suffers a major shoulder injury some time in the next couple of months.

Most of the other players on the roster offer at least a modicum of trade value. But not one represents a true cornerstone player, much less a cornerstone player either offering multiple years of cheap control, or signed to a highly team-favorable contract.

Not a single Yankee made my MLB Trade Value top-50 list this spring. That puts the Bombers in an ideal situation -- they can trade a passel of players, get real value in return that can help accelerate the team's turnaround and not worry about one of their own finding stardom in another uniform.

Start with the low-hanging fruit. Though his power binge from earlier in the season has slowed down a bit, Carlos Beltran remains one of the American League's most potent hitters in 2016. He's also 39 years old and a free agent at the end of this season, making him ideal trade bait. Given his age, he's one of the worst defensive outfielders in the league at this point, making him an ideal target for an AL contender who can slide him to DH at times, too. A reunion with the Astros could be a great fit.

Brian McCann has been the Yankees' third-best hitter this season and remains one of the league's best pitch receivers at age 32. He's also owed $17 million per year through 2018, and would be a lot more useful to a team trying to win now. The catching-needy Rangers could make sense, as could the Indians, if the Yankees were willing to eat a good chunk of McCann's remaining contract.

Starlin Castro has been a bad-to-terrible hitter three of the past four seasons and doesn't field or run well enough to offer any other kind of value. He's also just 26 and due an average of $11 million a year through 2019, which could make him worth a flyer.

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Nate Eovaldi is one of several Yankees pitchers with trade value. USATSI

But it's the pitching staff that's truly flush with tradeable assets. Nathan Eovaldi is just 26 and one of the hardest throwing starters in the game. He's also given us plenty of evidence that opposing hitters can smash 97-mph heat when gunned right down the middle, which could prompt the Yankees to let someone else fish for his potential.

Ivan Nova's no great shakes, but as a free agent-to-be he could be an improvement in the fifth-starter role for a team like the Orioles (assuming neither team sweats an intradivision deal in the age of two wild cards per league).

After that, players get harder to move ... but also a lot more desirable for other teams. By advanced metrics, Michael Pineda might be the Yankees' second-best starter. But he still gives up a ton of hard contact, he's a free agent at the end of next season, and in a market that's low on top-flight starting pitching, he could fetch a ton if the Yankees moved him now.

Andrew Miller is one of the best relievers in the game and a relative steal at $9 million a year. On the other hand, considering that just a couple months of Chapman landed so much talent, a team drooling over Miller through 2018 could empty their farm system for him.

In short, the Yankees have a clear path toward getting substantially better for the future. They could keep 26-year-old breakout shortstop Didi Gregorius, 27-year-old staff ace Masahiro Tanaka, fireballing reliever Dellin Betances (who can't even test arbitration for the first time until this winter), and a core of major league or near-major league young talent in Greg Bird, Aaron Judge, Luis Severino and others, and move pretty much anyone else who attracts full market value in trade.

The team that comes the other side would be much younger, offer the potential for sustainable success down the road, and maybe even pull the Yankees under the luxury tax, a move that thrust tens of millions of dollars back into ownership's pockets (they don't remotely need to worry about turning a healthy profit whether or not they do that, of course).

In what's shaping up as a fairly lackluster deadline week, the Yankees could make a gigantic impact if they go hard into sell mode. Now we just need to see if a team on the fringes of a playoff race will go that way. The alternative is to continue muddling along for two-plus more years, then hope that Bryce Harper and Manny Machado want to collect their $800 million worth of checks from the Yankees, and not anywhere else.