All eyes are going to be on Chicago right up until Monday's 4 p.m. ET non-waiver Trade Deadline, because according to reports, the White Sox are at least listening to offers on ace Chris Sale.
Any team hoping to acquire him would obviously have to empty its farm system to do so -- one report indicated Texas would have to begin with Nomar Mazara and Joey Gallo and keep adding from there -- and the White Sox would have to wonder if reloading for the future is worth significantly hurting their chances to win in 2017.
We can't answer that question here, and even if a move is made, we won't truly know whether it was the right decision for either side for years to come. But what we do have at our disposal is the ability to look back. When an ace has been traded midseason, has it worked out for the team that paid to get him? What about for the team that let him go?
The first step here is defining "an ace," and that's harder than it sounds. Some consider an ace to be the best pitcher on a staff, but it doesn't exactly fly that No. 1 Minnesota starter Ervin Santana is as effective as No. 3 Cleveland starter Danny Salazar. So here's how we approached this, beginning with the advent of the 30-team era in 1998.
To narrow this to find "traded aces," we looked only for…
1. All pitchers who had been on multiple teams in a year with 150 innings thrown (135 pitchers)
2. Of those, only the pitchers who were 10 percent better than average that year in both ERA and FIP (19 pitchers)
3. Of those, only pitchers who also had done both of those things at least one previous season, to weed out the "lightning in a bottle" types. (Sorry, 2014 Jeff Samardzija and 2003 Sidney Ponson.)
That left us with 12 names who had been included in 14 in-season trades. That seems like a pretty good number if we're just looking for the cream of the crop, and Sale would qualify under those requirements. Now, all that's left is looking at how those deals worked out. 
WIN-WIN

 1998: Randy Johnson traded by Seattle to Houston for John Halama, Freddy Garcia and Carlos Guillen.
For the buyer: Uh, yeah, that worked out. Houston won 10 of Johnson's 11 starts, as he struck out 116 and allowed 12 earned runs in 84 1/3 innings, and then he was also dominant in two postseason starts. Johnson may well have been the single most productive Deadline acquisition ever.
For the seller: Better than you probably remember. The bulk of Guillen's productive career came with Detroit, but he was a reasonably useful enough shortstop for several years in Seattle, Halama was a league-average starter for four years, and Garcia… well, he may not be remembered as an ace, but he was good enough in six years as a Mariner that he qualifies later for an ace trade of his own.

 2008: CC Sabathia traded by Cleveland to Milwaukee for Michael Brantley, Rob Bryson, Zach Jackson and Matt LaPorta.

For the buyer: Enormous win! The Brewers won 14 of Sabathia's 17 regular-season starts, as he posted a 1.65 ERA and threw a complete game on the final day of the season to win the National League Wild Card. Though he was hit hard in one postseason start, this was a deal Milwaukee would make again 10 times out of 10.
For the seller: At the time, LaPorta was seen as the big prize, but he fizzled in parts of four seasons with Cleveland (.238/.301/.393) and hasn't seen the bigs since 2012. Jackson pitched in only nine games with the Indians and never appeared again after 2009; Bryson never made it. So for a while, as Brantley spent the first few years of his career looking like an average player but not more, this looked like a huge bust. Of course, he eventually blossomed into one of baseball's better outfielders, shoulder injury notwithstanding. We'll call this one acceptable.

 2009: Cliff Lee and Ben Francisco traded by Cleveland to Philadelphia for Carlos Carrasco, Jason Knapp, Jason Donald and Lou Marson.
For the buyer: The first of many Lee moves sent a reigning Cy Young Award winner to Philadelphia in time for him to be dominant in the 2009 postseason, as the Phillies went to the World Series. That alone makes it a win, though it could have been a bigger one had the Phils just sat tight. When they traded him to Seattle that offseason, it was … well, the less said about that one, the better.
For the seller: At first? Bad. Real bad. Donald and Marson rode the bench for a few years, and Knapp never made it to the big leagues. Meanwhile, Carrasco spent the first five years of his Cleveland career struggling, getting suspended, being injured or some combination of the three. And that's how this deal would have ended ... if not for the semi-miraculous turnaround that Carrasco began in 2014, one that has made him one of baseball's elite starters since. This was a win, then; it just took way too long.
We're not done with Lee here, by the way. Not even close.
ONE-SIDED

 2000: Curt Schilling traded by Philadelphia to Arizona for Vicente Padilla, Omar Daal, Nelson Figueroa and Travis Lee.
Video: D-backs get Schilling in their best in-season trade
For the buyer: Franchise-defining! For Arizona, the benefit came not in the year that they acquired Schilling, but in the years after. (That Sale, like Schilling, has years of control remaining is a big factor.) Despite being in first at the time of the deal, the 2000 D-backs finished third, as Schilling was decent but far from great upon his arrival. But over the next three seasons, Schilling helped Arizona win the 2001 World Series and finished second in the NL Cy Young Award voting twice only because of teammate Randy Johnson. When he was later dealt to Boston, the D-backs at least managed to get back four decent relief seasons out of Brandon Lyon.
For the seller: Padilla pitched for the Phillies for five mostly competent seasons, making the 2002 All-Star team, while they got a season-and-a-half of league average starting from Daal and two-plus years of OK first-base production from Lee. Not a disaster. Far from memorable, especially with what Schilling would later achieve in Phoenix and Boston.

 2004: Freddy Garcia and Ben Davis traded by Seattle to Chicago White Sox for Michael Morse, Miguel Olivo and Jeremy Reed.
For the buyer: That's right, Garcia. Of all the names listed here, he's the one that stands out as not being remembered as an "ace," but he pitched 15 years in the bigs and finished third in the AL Cy Young Award voting in 2001. More importantly, Garcia meets our qualifications above, and he was a big part of Chicago's 2005 World Series team, so it's a win for them even though Davis did little.
For the seller: Morse had some nice moments in his career, but nearly all came with the Nationals and Giants. Olivo stuck around forever as a backup catcher, yet was rarely more, and Reed never panned out. This was a miss for the Mariners.

 2010: Cliff Lee and Mark Lowe traded by Seattle to Texas Rangers for Blake Beavan, Josh Lueke, Justin Smoak and Matt Lawson.
For the buyer: Hey, it's Lee again. In between Philadelphia stints, he went from Seattle to Texas, and once again, he helped his new team get to the World Series, piling up an insane 47/2 strikeout/walk rate in five postseason starts before departing via free agency. Even Lowe was useful, giving the Rangers good relief seasons in 2011 and '12. This was a risky deal for Texas that worked out.
For the seller: Nope. Can we just stop at "nope"? Smoak was to be the big prize, but he never developed in five years with Seattle, hitting .226/.308/.384, and he's now a bench player in Toronto. Worse, his career has easily been the best of the entire quartet the Mariners acquired; none of the other three have appeared in the bigs this year.
FORGETTABLE

 2010: Roy Oswalt traded by Houston to Philadelphia for Anthony Gose, J.A. Happ and Jonathan Villar.  
For the buyer: Lee had been traded to Seattle the previous offseason -- and fortunately for the Phillies, that deal won't show up here -- so Philadelphia ended up looking for another top starter to pair with Cole Hamels and Roy Halladay. Oswalt fit the bill and pitched very well down the stretch, providing a 1.74 ERA in 12 starts as the Phils got to the NL Championship Series. That was the end of his time as a top-flight starter, though. Oswalt was decent the next year, and then he was gone.
For the seller: It's been a long trip for everyone involved here, so the value the Astros got is less from these names, and more from what they turned into. Gose became Brett Wallace, who filled a spot and little more for parts of four seasons as Houston rebuilt. Villar showed flashes in parts of three seasons as the Astros' shortstop, but he didn't blossom until he went to the Brewers this year in a trade for Minor League pitcher Cy Sneed . Happ eventually become a solid starter with Toronto, but first he gave Houston three years of a 4.84 ERA. Advantage, Phillies?

 2012: Zack Greinke traded by the Milwaukee to Los Angeles Angels for Johnny Hellweg, Ariel Peña and Jean Segura.
For the buyer: Greinke was fine (3.53 ERA) but not elite for the 2012 Angels, who ended up third in the AL West despite winning 89 games; he just didn't move the needle all that much. After the season, Greinke would move on to sign with the Dodgers.
For the seller: Hellweg and Pena never did much for Milwaukee, so this is mostly about Segura, who provided an All-Star 2013 ahead of disastrous '14 and '15 seasons. He's currently having a rebound season in Arizona, while the Brewers are hoping for better performance from Chase Anderson and waiting on MLBPipeline.com's No. 7 Milwaukee prospect Isan Diaz. So far, this is a few months of Greinke for one good year of Segura. Not much to see here.

 2014: Jon Lester, Jonny Gomes and cash traded by Boston to Oakland Athletics for Yoenis Céspedes and competitive balance draft pick.
Video: PHI@OAK: Lester fans seven over seven vs. Phillies
For the buyer: Concerned about the depth of a rotation that was reliant upon Scott Kazmir, Jesse Chavez and Tommy Milone, the A's added Lester, soon after acquiring Samardzija and Jason Hammel from the Cubs. Though the narrative that losing Cespedes killed their offense was wildly overblown -- the offense had begun to fall apart well before he left -- this ended poorly for Oakland, which collapsed and finished 10 games out in the AL West -- though Lester was effective with a 2.35 ERA
For the seller: With the Red Sox on the way to 91 losses, selling the last few months of Lester's contract for the chance to have Cespedes for all of 2015 made sense. Unfortunately, it backfired, because Cespedes never seemed comfortable after the trade (though he did eventually turn into Rick Porcello that offseason), and the deal put an end to hopes that Lester would sign long-term with Boston. They've been trying to fill that hole ever since.
LOOKS AWFUL, BUT…

 2002: Bartolo Colon and Tim Drew traded by Cleveland to Montreal for Cliff Lee, Brandon Phillips, Grady Sizemore and Lee Stevens.
For the buyer: The Expos gave up way, way too much in this deal, but considering the circumstances, it's pretty difficult to fault them. If you've forgotten, at the time the future of the franchise was so uncertain that it was difficult to worry about far-off prospects when no one knew if the team would even exist. Colon pitched perfectly well (3.31 ERA in 17 starts) as Montreal mounted an ill-advised playoff push, yet who could blame them? 
For the seller: If this isn't the biggest haul in a single deal in baseball history, it's close -- though Cleveland didn't maximize the value considering that nearly all of Phillips' great career has come across the state in Cincinnati.
TOO SOON TO SAY
These deals have all come in the past two calendar years, so we still can't say we know for sure how they'll turn out. What if Willy Adames, currently MLBPipeline.com's No. 2 Tampa Bay prospect, becomes a star? How will all those Rangers prospects who went to Philadelphia progress? We don't know yet. But based on how they look so far...

 2014: David Price traded by Tampa Bay to Detroit as part of 3-team trade. (Tampa Bay received Drew Smyly and Willy Adames from Detroit, and Nick Franklin from Seattle. Seattle received Austin Jackson from Detroit.)

For the Tigers, Price was his normal outstanding self, giving 223 1/3 innings of a 2.90 ERA, pitching well in the playoffs, and then bringing back another big return, arguably turning a profit on the entire endeavor, as you'll see. So far, it hasn't looked as good for the Rays, who got two seasons split between injury and elite performance from Smyly before a poor 2016, and very little from Franklin -- though none of the trio, including Adames, is older than 27 even now.

 2015: Cole Hamels, Jake Diekman and $9.5 million traded by Philadelphia to Texas for Alec Asher, Jerad Eickhoff, Jorge Alfaro, Jake Thompson, Nick Williams and not having to pay Matt Harrison approximately $40 million.
So far, both sides are probably thrilled by this. Hamels has been the ace Texas wanted, particularly with Yu Darvish hurt, Diekman's 2.31 ERA in 69 games for the Rangers means he was no throw-in, and Harrison's back hasn't let him pitch at all since the trade, making his contract an anchor. Meanwhile, the Phillies have kickstarted their rebuild and have already received impressive contributions from Eickhoff.

 2015: David Price traded by Detroit to Toronto for Matt Boyd, Daniel Norris and Jairo Labourt.
Here's Price again, and considering what he did for Toronto, Boyd and Norris could turn into the next Koufax and Drysdale and they might not mind. (OK, maybe they would.) Price was dominant as the Blue Jays marched to their first postseason in 1993, though they eventually fell short of the World Series. Boyd and Norris have both appeared in Detroit's rotation, though it's too soon to say what they'll become.

 2015: Johnny Cueto and $1 million traded by Cincinnati to Kansas City for Brandon Finnegan, John Lamb and Cody Reed.

The Royals didn't really need Cueto (or Ben Zobrist, for that matter) to get to the postseason. They just needed them to win in the postseason. Given that the Royals all just visited the White House to collect their rings, that alone makes it a success, even though Cueto's performance was uneven before a dominant complete game in Game 2 of the World Series. The lefties received by the rebuilding Reds have been three of their six most-used starters this year.