In one of the most shocking blockbusters in MLB trade deadline history, the Oakland A’s sent All-Star Yoenis Cespedes and a competitive balance pick to the Boston Red Sox for Cy Young contender Jon Lester, former Athletic Jonny Gomes, less than $1 million, and a gold-plated protective case for Billy Beane’s giant balls.

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Earlier this month, the A’s pulled off what had been the biggest trade of the 2014 season, sending top shortstop prospect Addison Russell and three other young players to the Cubs for right-handed starters Jeff Samardzija and Jason Hammel. As I wrote at the time, the A’s were leading the American League in ERA and park-adjusted ERA when that deal went through, but still recognized the tenuous nature of their starters’ performances, including the unlikelihood that journeyman righty Jesse Chavez would keep putting up dominant numbers.

Unsurprisingly, the A’s were right, and Chavez has since turned into a pumpkin. After flashing an elite 2.71 ERA through his first 15 starts and strong strikeout-to-walk rate and solid peripherals to match, he’s posted a 5.51 ERA over his last six outings. And that doesn’t even tell the full story: In his last three starts, Chavez faced two of the AL’s weakest lineups, battling the punchless Mariners once and the feeble Astros twice. He failed to make it to the sixth inning in any of those three starts, and completed six innings only once in his last six. An underrated element of a starting pitcher’s value is his ability to soak up innings, and the possibility of Chavez forcing the A’s to burn through their bullpen every fifth day and risk having an army of dead-tired relievers come playoff time wasn’t something Beane and Oakland’s sharp baseball operations crew could afford to face.

Of course, the notion of “come playoff time” looms larger than any other factor. According to ESPN’s playoffs odds, the A’s — who own the best record (66-41) and run differential (plus-162) in baseball, the latter by a mile — currently have a 99.6 percent chance of making the postseason. The one rub: The A’s happen to play in the same division as the Angels, who’ve been the second-best team (63-43, plus-89) in the majors this year. While Oakland looks like a playoff lock regardless, its chances of reaching the World Series will increase considerably if it wins the division and earns home-field advantage, and Lester can help the team maintain its current 2.5-game lead over the Halos and avoid a one-game wild-card playoff. Given what we know about the A’s appetite for big deadline deals and their frustration over repeatedly coming up short in October, acquiring a true ace to help fend off the Angels in the regular season and to be the go-to guy during the playoffs makes considerable sense.

Lester, a free agent after this season, has already expressed his interest in re-signing with Boston, and will be out of Oakland’s price range regardless. He’s a rental for a team committed to going for broke. Still, even in a short stint, he’ll bring the A’s considerable value. In Lester, the A’s are getting a pitcher who ranks fifth in the AL in ERA (2.52) and fourth in Fielding Independent Pitching (2.62) this season. Lester has slashed his walk rate to just 5.5 percent (two per nine innings) in 2014, the lowest mark of his career. He’s also generating more whiffs with his four-seam fastball than he has in five years, while doing something few 30-year-old pitchers can pull off: maintaining about the same velocity he boasted when he first started firing bullets in the big leagues.

What’s more, Lester managed that as a left-handed pitcher taking the mound in front of the offense-inflating Green Monster; going from that environment to the more pitcher-friendly confines of Oakland’s O.co Coliseum could help his numbers even more. He’s also going to be pitching in front of a better defense, going from the team that is tied for fifth in the AL in Baseball Info Solutions’ Defensive Runs and fifth in Ultimate Zone Rating to the team that ranks second in the AL in both of those metrics.

Of course, some of Oakland’s defensive edge will dissipate after sending the slick-fielding Cespedes to Boston and replacing him with the defensively challenged Gomes. That swap will obviously cost Oakland offensively, too. After a huge 2012 campaign in which he hit .262/.377/.491, the 33-year-old Gomes has tailed off, batting just .234/.329/.354 this year; by wRC+, a stat that tallies all of a player’s offensive contributions and adjusts them for park effects, Gomes has gone from being 43 percent better than league average offensively two years ago to being 8 percent worse this season. Still, Gomes has his uses. The longtime lefty-masher is hitting .302/.400/.431 against southpaws in 2014 after crushing them at a .277/.387/.494 clip from 2011-13, and he’ll give Oakland a dangerous pinch hitter and occasional platoon guy against the better lefties in the league.

The A’s will be able to platoon Gomes because they didn’t stop with the Lester deal. About an hour after coming to terms with the Sox, Beane parlayed his newfound pitching surplus into a little more outfield help, shipping Tommy Milone — who’d been stranded at Triple-A since the Samardzija-Hammel deal — to Minnesota for Sam Fuld. This looks like a steal for the Twins, who just swapped a 32-year-old outfielder they grabbed off waivers in April for a 27-year-old lefty starter who’s controllable through 2018. But that perception surely doesn’t matter to Beane, who just turned a guy he doesn’t have room for into a player who perfectly complements Gomes. While Milone’s surface stats look impressive, his FIP is nearly a run higher than his 3.55 ERA, and nothing suggests he’ll amount to more than a back-end starter. Meanwhile, though the veteran Fuld doesn’t hit much, he’s an ace defender and a jackrabbit on the base paths, and he’ll give Oakland much-needed outfield depth, especially with reserve Craig Gentry out until mid-August with a broken hand.

While Fuld will spend most of his time in center, Cespedes’s abandoned spot will likely go to a committee of players, befitting Oakland’s reputation for valuing depth and flexibility more than perhaps any other team. Josh Reddick, who was stuck in a deep offensive funk last year and early this season but has hit .275/.328/.505 since May 9 and plays excellent defense, now has a clearer path to playing time. So, too, does Stephen Vogt, who has gone from being a bit player in the Rays organization to being a key member of a potential World Series winner in the span of 15 months, hitting a massive .351/.381/.530 in part-time duty this year. Vogt’s aberrant .366 batting average on balls in play might mean his 2014 success is a fluke, but even that figure has some meat behind it: According to ESPN research, Vogt’s .250 hard-hit average (simply, the frequency with which a batter hits the ball hard) ranks second in MLB this year, behind only Detroit’s Victor Martinez.

All in all, while losing Cespedes’s combination of power and defense will hurt, the A’s have enough quality outfielders and overall roster strength to cover for his absence. What’s more, they might actually improve in one area that Beane values considerably: on-base percentage, where Cespedes carries a feeble .303 mark this year and posted a .294 figure last year. And hey, let’s be honest: For a team that’s trying to win it all, sweating a left-field platoon is a pretty small price for an ace of Lester’s caliber.

As meaningful as this deal is for Oakland’s title push, let’s not lose sight of the other side: That ace came from the defending world champions, who’ve dealt four-fifths of their original 2014 starting rotation in the past week:

It’s hard to blame GM Ben Cherington for embracing the fire-sale approach. The Sox sit in last place in a weak AL East, with a 48-60 record and abysmal minus-55 run differential. Even if Lester leads the A’s to World Series glory, it still looks like the Sox made out like bandits in this deal. Boston’s lowball contract extension offer to Lester went nowhere this spring, and management seemed to have little interest in coming back with an offer in the vicinity of Cole Hamels’s six-year, $144 million deal. With the Sox falling out of the playoff race and a deal unlikely to be reached in the next two months, it was a near lock that Lester would be dealt somewhere. To get a 28-year-old, tools-stuffed outfielder and a high draft pick in exchange for a two-month rental looks like highway robbery at a glance. Especially given this:

Cespedes gives the Sox the power source they’ve sorely lacked, plus the kind of elite defender they thought they were getting when they pissed away $142 million on Carl Crawford. And Cespedes’s power potential is even more intriguing considering what he could do with the Green Monster beckoning 81 times a year:

The sole issue here is how long the Sox will get to keep Cespedes. Though he’s in only his third year of major league service time, he has a special clause in his four-year, $36 million contract that means he can test free agency at the end of the 2015 season; his deal doesn’t even allow for a qualifying offer that would net a draft pick if he signs elsewhere. Essentially, Gomes, the competitive balance pick, and the cash aside, this deal boils down to two-plus months of Lester for 14-plus months of Cespedes.

Those 14-plus months offer all kinds of possibilities, however. First, consider payroll. Boston will shave a good chunk of money off its commitments at season’s end, including Lester’s $13 million salary (already gone) and Stephen Drew’s prorated $10 million salary. Cespedes is set to make $10.5 million next year, which means the Red Sox can either carry that favorable salary and benefit from his production or try to flip him to another team between now and Opening Day 2015.

If one thing is clear, it’s that the Sox won’t hesitate to keep dealing. A couple of hours after moving Lester, Boston sent veteran right-hander John Lackey and left-handed prospect Corey Littrell to the Cardinals for Allen Craig and Joe Kelly. I covered Lackey’s value in Wednesday’s trade deadline primer, but to recap: The Cardinals, who also acquired Justin Masterson from Cleveland on Wednesday, are not only getting an above-average starter for this year and next in Lackey, but also a huge bargain, as Lackey’s salary will drop from nearly $16 million this year to the league minimum in 2015 due to an injury clause in Lackey’s contract.

As they did in the Lester deal, the Sox opted for established major leaguers over prospects in the Lackey deal. Unsurprisingly, it’s hard to feel nearly as good about the Lackey haul as it is the Lester haul. I looked at both Craig and Kelly in last week’s NL Central roundup, and there’s not much encouraging news to report. Starting on Opening Day 2015, Craig will have three years and $25.5 million left on his five-year contract, with a $13 million club option for 2018. When he was hitting like the most “clutch” player in the known universe, those terms looked like an unbelievable bargain. Now, with those wildly unlikely RISP numbers and his ability to hit for average and power mysteriously absent, Craig looks more like a spare part than a star, and like someone the Cards were easily willing to sacrifice to make room for outfield phenom Oscar Taveras. The Sox are obviously banking on a return to form for Craig, who at age 30 still offers right-handed power potential for a team that sorely needs it, even after adding Cespedes. As for Kelly: While the 2.69 ERA he posted last season looks like a fluke given his mediocre peripheral numbers, he’s controllable through 2018 and offers the kind of cheap, decent numbers that teams want from a no. 5 starter.

We know the Red Sox can lose big and then reload brilliantly in a short span, because they just did it, going from worst to first in 2012-13 thanks to blockbusters and a series of small, shrewd moves alike. Even with a few top prospects graduating to the majors this year, Boston’s farm system is still stacked, creating all kinds of intriguing trade possibilities this winter. The Sox, like nearly every other team, covet young(ish) stars and would love to add more to the roster. Unlike most other teams, the Sox have enough talent in the minors (particularly after sending Jake Peavy to the Giants last week) to make a huge deal for someone like Troy Tulowitzki or Giancarlo Stanton.

Boston built intelligently and caught a bunch of good fortune in winning an unlikely World Series last year. Getting Cespedes could be the first step toward another strong reloading process. And if the Sox and Lester were to find a happy meeting place in negotiations this winter, well, that would be a neat little trick too. Those are the kinds of options and hypotheticals a team hoping for another quick turnaround wants at its disposal, and if everything breaks right, next season could bring a fourth championship in 11 years.

This season, though, all eyes will be on the A’s, who are vying for their first title in 25 years, and their first in the Moneyball era. If Beane’s shit comes up short again this October, it won’t be because he didn’t try.