When the Royals traded away Wade Davis in a one-for-one swap for Jorge Soler in December of 2016, the trade looked like a win-win. The Cubs needed a closer and had an extra young, cheap outfielder. The Royals had Kelvin Herrera presumably ready to step in at closer but needed some offense to make one last run with their core.

For the Cubs, the deal worked out as expected. In 2017, Davis had a very good year for a very good club. For the Royals, however, the trade went less well. Herrera struggled — and, even though Scott Alexander and Mike Minor exceeded expectations, the team probably missed Davis to some extent. Soler, meanwhile, played poorly, ultimately passing much of the season at Triple-A. The Royals ended up finishing just five games out of the Wild Card. If they had gone 11-8 against the Twins instead of 8-11, they might have had one last chance at October.

Soler is now off to a great start in 2018, and the Royals control him at a low cost for the next four seasons, although there is a reasonable argument to be made that winning the trade is impossible at this juncture. The Davis trade diminished the the Royals’ chances of winning a division title, prevented the club from receiving a compensatory draft pick, and led the team to trade away Esteury Ruiz, Matt Strahm, Travis Wood, and cash for Ryan Buchter, Trevor Cahill, and Brandon Maurer. Cahill didn’t work out with the Royals, Maurer is off the 40-man roster, Buchter was sent to the A’s with Brandon Moss for Jesse Hahn — currently on the 60-day disabled list — and Heath Fillmyer. That’s the road the Royals traveled down last year, it did not work, and now they are terrible and likely several years away from contending.

Concluding that the Davis-Soler trade is already a loss for Kansas City requires some hindsight analysis. Davis was hurt in 2016, and his performance in 2017 was far from a guarantee. There is an alternate, even reasonable, scenario where Herrera pitches well in 2017, Soler provides solid production in an outfield corner, and the money saved on Davis’s salary that went to (which went to Moss and Wood) produces two more contributors to a potentially contending team. Davis didn’t get hurt, Herrera wasn’t great, Wood didn’t pitch well, and Soler and Moss combined for -1.4 WAR on the season. The plan didn’t work out, but it was at least defensible in terms of competing in 2017 with the added benefit of acquiring a future asset in Soler.

After a .144/.245/.258 season with a 32 wRC+ in 110 plate appearances, Soler has authored a gigantic turnaround. In 133 plate appearances this year, the Royals right fielder is hitting .324/.436/.546 with a 166 wRC+. That batting line is greatly helped by a .411 BABIP; however, the 16% walk rate, a reduced 24% strikeout rate, and an ISO above .200 provide a solid base for Soler to be a productive hitter if fewer balls drop in for hits. In terms of projections, Soler’s fast start has eliminated his awful 2017 season. When the Royals traded for Soler, he had just finished a season where he put up a 105 wRC+. Entering the year, he was projected for a 98 wRC+, but he’s already back up to 107 for the rest of the season.

As for how Soler has made such dramatic changes to his fortune, he lost some weight and reworked his swing. Maria Torres of the Kansas City Star discussed the change with Soler in the offseason and wrote the following.

Now Soler bears down on his back foot more, taking his stance a bit off-center to see the pitch on a level that’s more even with his gaze. His depth perception is better than it’s ever been. Ideally, he’ll have a higher success rate on pitches thrown inside now that his barrel is quicker to the ball.

Let’s see if we can determine how that alteration has manifested itself. Here’s an inside fastball from 2017:

That pitch is inside, but not by much, nearly catching the corner of the plate. In trying to get his arms extended, Soler is unable to get the barrel of the bat on the ball or get his bat square enough to keep the ball fair. Here’s a very similar pitch from this season:

Soler gets the barrel on the ball with a more compact swing. The ball stays fair and goes a long way.

Soler has long been a fairly patient player, taking a lot of pitches and recording a lot of walks. The same has held true this season, although he is swinging and making contact at more pitches in the zone. That’s reduced his strikeouts, perhaps due to his swing changes. Despite more swings in the zone, he’s been able to increase his walks because he is seeing quite a bit fewer pitches in the zone. His nine-game walk streak earlier this year represents the longest of the season and one of the longest of the last four seasons, as shown in the table below, per Baseball Reference.

Almost all those players are good hitters. Some of them are great. A streak might be a bit fluky, but Soler’s patience has been consistent. We can look at a hitter’s batting line and see that he is performing well, but we can also look at how a hitter is being pitched to get an idea of how dangerous the opposition believes he can be. Soler is seeing fewer fastballs this year and more pitches outside the strike zone. Here’s Soler’s pitch heat map from last year:

It certainly doesn’t look like pitchers were too afraid to come after Soler last season. Here’s what the same chart looks like this season, from Baseball Savant:

There’s still a bunch of pitches in the middle, but there are a lot more pitches outside the strike zone, too, particularly away. Pitchers don’t seem as willing to challenge Soler as they were a year ago. There’s some reason to believe the 26-year-old is going to keep hitting. Soler’s .222 ISO is actually lower than his expected ISO based on launch angle and exit velocity. Of his 13 extra-base hits, nine are doubles; just four are home runs. If a few more doubles turn into home runs, the power has potential to grow and mitigate some of the damage to Soler’s batting average when the BABIP drops.

Jorge Soler entered the season with a 96 wRC+ and a 0.8 WAR in 875 plate appearances. He wasn’t quite replacement level, but he was pretty close. With his good start, even if he merely hits his modest projections the rest of the way, he’s going to be an above-average player this season. While last season didn’t go the way Soler or the Royals would have preferred, Soler has turned things around and, with four more years on the Royals, he might last long enough to be on the team the next time the Royals are trying to contend.