An afternoon trade went down between the Rangers and the Braves. One very much legitimate way of thinking about it: Lucas Harrell isn’t very good, but the back of the Rangers’ rotation lately has been terrible, and this just goes to show how the market for any half-decent starting pitcher right now is inflated. While Travis Demeritte isn’t a top-10 prospect or anything, he is a former first-rounder having a breakthrough season in High-A. Not a lot of available 21-year-olds with that sort of power. Good get for the Braves, considering they just added Harrell for practically nothing a couple months ago.

Another very much legitimate way of thinking about it: The Rangers didn’t want to pay the high price for an established relief arm, so they found an alternative route, landing in Dario Alvarez a potential front-line lefty bullpen weapon. Harrell gets attention as the starter with experience, and Demeritte gets attention as the prospect stepping forward, but Alvarez might be a hell of a pitcher, considering you might not have ever heard of him.

Earlier last year, the Ranger bullpen was problematic, and a big part of the turnaround were the quiet additions of Jake Diekman and Sam Dyson. The bullpen actually turned into a strength, allowing the Rangers to surge forward into the playoffs. The bullpen this year reverted to mediocrity, and as I write this it’s second-worst in the majors in WAR. By WPA, it’s been in the middle of the pack, but clearly the Rangers could use improvement. And think about the market. You want a proven late-inning arm? Most people believe the Cubs overpaid for Aroldis Chapman. The Yankees have put an impossible price tag on Andrew Miller. The Royals have done the same with Wade Davis. Quality relievers are all the rage, and the market seems to reflect that. If you want someone you know will be great, it’s going to require a truckload of value.

Proven relievers are costly. Dario Alvarez is an unproven reliever. The funny thing about being proven is all that proof has taken place in the past. The Rangers are focused on the next few months, months occurring in the future, and Alvarez doesn’t have no experience. He was up with the Braves since the middle of June. He pitched well. The following list is factual, technically.

Highest strikeout rates, 2016

I didn’t make any of that up. The only thing I did was set my own minimum number of innings, because this year in the majors, Alvarez has thrown all of 15. It’s not enough to make him “proven,” especially given his limited history. And another mark against Alvarez is he was only pitching with the Braves because they claimed him off waivers in the last week of May. Just a couple months ago, Alvarez looked like a live but wild arm, nearly unwanted. The Braves have made him look better. His velocity is up from where it’s been before. And since Alvarez returned to the majors, he’s been almost untouchable. It’s hard to fake all those strikeouts. The Rangers are taking a chance on missed bats.

While I’m trying to sell you on Alvarez, here’s a hand-picked comparison to a lefty reliever you know.

A Comparison Pitcher K% BB% O-Swing% Zone% Contact% PA 2015 Aroldis Chapman 42% 12% 33% 46% 60% 278 2016 Dario Alvarez 46% 8% 36% 45% 60% 61

If it weren’t for, you know, the horrible, inexcusable behavior, that Chapman would’ve fetched a ton in a trade. A slightly different version of Chapman just did fetch a ton in a trade. The most important column here is arguably the last one — that’s the one that reveals Alvarez’s limited sample size. But I think all the other columns are also important. Alvarez has some statistical things in common with one of the best relievers we’ve seen. It’s way, way too soon to actually buy into him, but at some point, an unproven good player becomes a proven good player, if the performance holds. The Rangers are buying Alvarez early, but they have to love what he’s done.

As noted, Alvarez’s velocity is up from brief appearances in 2014 and 2015. And while that’s pushed his fastball into the mid-90s, Alvarez has relied on his slider, throwing it 61% of the time. He’s tied for the highest slider rate in the game, with one Andrew Miller. Here’s what the slider can look like:

One area where Alvarez hasn’t excelled has been getting ahead, but it hasn’t badly cost him. And unlike so many other lefties, Alvarez hasn’t shown a horrible split — he’s struck out 16 of 36 righties. You can see shades of Chapman, and you can see shades of Miller. These are only shades, and Alvarez doesn’t have, say, Miller’s pinpoint command, but dominance is dominance, and the Rangers have a chance here to have purchased a dominant reliever before other teams realized what was happening. For Alvarez, it would be a quick ascent, but he’s always gotten strikeouts in the minors, and he wouldn’t be the first pitcher to have the strike switch flipped.

Even though Alvarez is cost-controlled, it does make sense for the Braves to move him — few relievers should ever be considered long-term assets, and the Braves are nowhere close to winning. Alvarez is a win-now player, and the Rangers are trying to win now, and while Alvarez could also be a win-tomorrow player, he’s a hard-throwing reliever who leans on his slider. You know how these things can go. The Braves exchanged a promising reliever for a promising hitter. They improved Alvarez in two months and turned him into a young infielder with power and a strikeout problem. That’s a solid flip, the sort that rebuilding teams live for. The Braves made a sensible move for them. The Rangers made a sensible move for them.

I’m not saying that Dario Alvarez is absolutely, unquestionably great. That would be silly. I’m just saying he might be getting there, on account of all of the strikeouts he’s picked up. For the Rangers, he’s a cheaper alternative to a costly, proven solution. Being proven doesn’t win a World Series.