There’s a fairly prevalent belief that teams should be reluctant to trade with other teams in the same city. Something to do with rivalries, or whatever. You don’t want to have a valuable former asset helping out some other club just a few miles away. Indeed, if you examine trading histories, these moves are fairly uncommon. Baseball has established a precedent by which intra-city ballclubs seldom come together for a swap. However, that’s stupid. The Cubs and White Sox realize that’s stupid, and so, as of Thursday morning, we’ve got ourselves a blockbuster.

Cubs get:

White Sox get:

It’s long been fairly obvious that Quintana was going to get moved. While he’s a long-term asset, he’s really a short-term asset under long-term control, and the White Sox probably would’ve liked to have moved him last winter. Seeing Quintana get dealt isn’t surprising. It’s also not surprising to see the Cubs jump on a cost-controlled, somewhat young starter. This has been the rumor for what feels like years. They developed their bats, and they’ve needed to acquire pitching. Quintana is said pitching. Everything about this makes sense, once you move beyond whatever shock you might feel about the two Chicago teams reaching an agreement. This is a sensible exchange. It’s also a total doozy.

One truth that can’t presently be escaped: the Cubs aren’t in a great place in the playoff picture. They’re 5.5 games behind the Brewers in the division, and they’re 7.5 games behind the Rockies in the wild card. There’s less than half of the season to go, so on paper this is unusual — midseason additions tend to be made by teams in better places. But, well, you probably know how this goes. The Cubs are the defending champions, and they’re presumably better than the Brewers. They’re presumably better than the Rockies. So, they ought to make up ground. The projections still like them plenty. And there’s also the matter of Quintana not just being a 2017 addition. The Cubs could have him through 2020 if they like, which is important given their aging rotation. Quintana helps now, and he helps later, so again, we come back to the point that this makes all the sense in the world.

Whenever we write about Jose Quintana, we’re almost obligated to note that he’s been underrated. We’ve perhaps called Quintana underrated so many times that he’s no longer underrated, but I don’t think that’s accurate, because even just reading responses elsewhere to this news, Quintana still isn’t considered all that much. I understand that his ERA this season is up. I understand he’s not a big strikeout dynamo. But I can’t find any actual decline in his stuff. Quintana is pitching the same as ever, and he has perhaps worse catchers than ever. Seems to me, he’s fine. And, what is Jose Quintana, exactly? Over the past three years, he ranks seventh among all pitchers in WAR. Over the past two years, he ranks ninth among all pitchers in WAR. In the rest-of-season projections, he again ranks ninth among all pitchers in WAR. Quintana’s plenty good. And if you want another way to think about him, this should help:

Past Three Years Pitcher Starts IP/Start WAR K% BB% K-BB% Strike% IF/FB% HR/FB% Fastball (mph) Jose Quintana 96 6.3 13.9 22% 6% 16% 64% 11% 9% 91.8 Jon Lester 97 6.3 13.4 25% 6% 19% 64% 10% 11% 91.8

Over the past three years, Quintana and Lester have basically been the same guy. Lester has gotten a few more strikeouts, but he’s also been in the National League, and Quintana has suppressed more home runs. By value, they’ve been virtually identical, and while Lester was born in 1984, Quintana was born in 1989. It stands to reason Quintana might have more left in the tank. And then there’s the money. This is where it’s easy to get tripped up. It’s easy to forget about how player value is a function of both ability and contract commitment. The Cubs signed Lester as a free agent for six years and $155 million, with a seventh-year option. Here’s what Quintana has:

2017: $7 million (less than half remaining)

$7 million (less than half remaining) 2018: $8.85 million

$8.85 million 2019: $10.5 million club option ($1 million buyout)

$10.5 million club option ($1 million buyout) 2020: $10.5 million club option ($1 million buyout)

It’s absurd how team-friendly that looks. It’s not Quintana’s fault, and remember he’s been dropped by both the Mets and the Yankees — there’s nothing wrong with just wanting long-term cost certainty. Quintana will never have to worry about money again. But a huge part of his appeal is that, relative to his performance, he is just massively, massively underpaid. Even after this year, he’s under contract for about three years and $30 million, and it’s even more team-friendly than that, since there are buyouts in case anything goes wrong. And then there’s the second half of 2017, too. The stretch run. Possibly or probably the playoffs. Quintana is good, Quintana is durable, and Quintana is cheap. His contract will give the Cubs more flexibility down the road as their young core becomes increasingly expensive. It’s not always easy to develop and maintain a long-term core while staying under the luxury tax.

So, Quintana is very good. I can’t see any reason why he should be considered worse now than he was in 2016. According to the expected wOBA numbers at Baseball Savant, Quintana now is the same. He’ll provide a measure of certainty, given the issues with Lester, Kyle Hendricks, Jake Arrieta, and John Lackey. For the privilege of using Quintana every five games or so, the Cubs are paying a hefty price. To look at this from the White Sox’s perspective: Last winter, when they traded Chris Sale, they got Baseball America’s No. 2 prospect, and the No. 32 prospect, along with two other pieces. Now, in moving Quintana — and referring to the updated midseason list — they’re getting the No. 5 prospect, and the No. 83 prospect, along with two other pieces. The package isn’t as valuable as the Sale one, in large part because Cease isn’t considered as good as Michael Kopech. But the most valuable prospects in the game are highly-ranked position players. Jimenez is within shouting distance of Yoan Moncada.

In fairness, this return contains plenty of risk. Jimenez, Rose, and Flete have all been playing in High-A. Cease has been playing in regular A. These aren’t players who have seen much in the way of advanced competition, and so there is any number of ways for things to go wrong from here on out. But in the White Sox’s rebuild, they’re shooting for the moon, and Jimenez comes with that enviable upside. It’s even partially informed by Statcast.

Jimenez briefly made headlines for having a batted ball tracked at 119.4 miles per hour. Now, it was actually just a ground ball, and there’s some possibility the number is wrong. I don’t want to make *too* much of it, but let’s just say, for the moment, that it happened, and the number is right. Immediately, that number on its own is meaningful. That number would reflect Jimenez’s raw power, or bat speed. Very few players have reached such an exit velocity — that’s Giancarlo Stanton or Aaron Judge territory. It’s also Peter O’Brien territory. Prospects are risky. You know how this goes.

But Jimenez is 20 years old, and while he strikes out, he doesn’t have a strikeout problem. Right now he has a career-high walk rate against the highest level of competition he’s faced, and the scouting reports have long lauded him for his bat speed and strength. Jimenez might not ever win a Gold Glove in the outfield, but there’s no better trait than big power, and his is some of the biggest. Don’t go too far down the Judge path; players don’t work out as well as Aaron Judge. It’s just that Jimenez could be a good one, quickly. Power like his gives a hitter a rather large margin of error.

Cease is a young hard-thrower with a curveball. He gets a whole bunch of strikeouts while allowing too many walks, so he’s still a few tweaks away. There’s plenty for Cease to prove before he’s given a shot to be a long-term big-league starter. Rose is a first baseman with proven power. Flete is a versatile infielder with new power. Flete has 14 career professional home runs since 2012, and he’s hit 12 of them since last July. At least statistically speaking, he’s rising, so you shouldn’t dismiss him as a throw-in. Flete could be turning into something; any of these players could become something.

The grandest hopes are pinned on Jimenez. And when you allow that no prospect is perfect, he’s about as good as the White Sox could’ve hoped for. He’s a young slugger with an improving eye and light-tower power, and maybe, in a few years, he’ll be as good in the majors as Jose Quintana is already. Around when, you know, the White Sox are ready to be something. From the White Sox side, you see Jimenez, and you drool. From the Cubs side, you see Quintana, and you also might see that Jimenez could have a little too much Jorge Soler. Every prospect is a risk, and Quintana can help a good ballclub tomorrow.

Say this for Quintana — he probably won’t be underrated anymore. Not if he keeps pitching well, not in that jersey. The Cubs see him for what he is, and they’ve so added another core piece. The White Sox also saw Quintana for what he is. They held out long enough to get a little uncomfortable, but in the end, they’ve made the splash they knew all along they could make.