Strictly based on WAR, the top middle-infield tandem so far has been playing half the time in Miami. The season hasn’t been a complete disaster for the Marlins, because they’ve observed steps forward by Dee Gordon and Adeiny Hechavarria, and that bodes well for the future, if the present is a little bit shot. Also based on WAR, the Marlins’ lead is about as small as it gets. Right on their heels is the Giants’ tag-team of Brandon Crawford and Joe Panik. The difference is something like one-tenth of one point. Let’s not split figurative hairs.

It’s a really interesting evolution that’s taking place in San Francisco. Crawford’s offensive development has been something to behold, starting out as a glove-first shortstop with a better bat than most pitchers. Crawford, now, is one of the best shortstops in baseball, provided the season doesn’t wear him down. But any attention paid to Crawford is attention not paid to Panik. And while Panik didn’t begin his big-league career in the same sort of way, he’s also reaching a level at the plate few would’ve imagined. Joe Panik isn’t just a slap hitter. Joe Panik is a genuine threat!

When the Giants first promoted Panik to the majors, they admitted they didn’t think he was ready. He was just going to get some on-the-job training, as the Giants were desperate, and you can see now how quickly Panik has adjusted to the competition level. This isn’t the point of the article, but here are the top three lefties hitting against lefties since the start of last season (by wRC+):

Anthony Rizzo Brandon Crawford Joe Panik

In seventh, by the way, is Nori Aoki. It’s not a coincidence. The Giants have a plan here, and it would be tough to argue it isn’t successful.

Even the rushed version of Panik held up. Last year, he was an above-average hitter, spraying the ball around and making a ton of contact. But conclusions were reached about his ceiling, because he went deep just once in nearly 300 regular-season trips to the plate. It didn’t appear Panik had power. Guys who don’t have power have trouble drawing consistent walks. Guys without power and walks have low offensive ceilings. No reason Panik couldn’t be useful, but I’d say he fell short of exciting.

In March, an answer to a question, and an answer of certain intrigue, in hindsight:

Over time, my swing is actually going to lead to more power. I’m not too concerned about that right now.

Panik homered on Sunday. He homered last Wednesday. He’s up to four homers, in far fewer plate appearances than a year ago, and he’s more than doubled his isolated power. Of maybe even greater relevance: Panik has lowered his groundball rate 11 percentage points, and he’s increased his fly-ball rate 12 percentage points. It’s one of the biggest fly-ball-rate increases in baseball, and that’s the sort of thing that tends to mean something.

Panik is changing, and Panik is growing. Under the eye of Hensley Meulens and the rest of the coaching staff, Panik is hitting the ball with more selective authority, and he hasn’t even sacrificed any contact. While Panik will never blossom into a slugger, he can turn into a guy who slugs more pitches, and here let’s take a look at some big swings in approach.

In the following plot, you’ll see 2014 compared against 2015. There are two statistics. The first one is groundball rate on pulled batted balls. The second one, somewhat related, is pull rate on all fly balls.

The simple takeaway: far fewer of Panik’s pulled batted balls have been on the ground. And when he’s hit a fly ball, he’s been a lot more likely to hit it toward right field.

Maybe these rates don’t mean much to you. Let’s put them in context by considering percentile ranks. First, for groundball rate on pulled batted balls:

2014: 88th percentile

88th percentile 2015: 9th

Panik went from one of the highest rates in baseball to one of the lowest rates in baseball. That one’s easy. Now, for pull rate on fly balls:

2014: 1st percentile

1st percentile 2015: 64th

Panik went from one of the lowest rates in baseball to a rate comfortably in the upper half. A year ago, Panik just about never pulled a fly ball. Now he still doesn’t do it frequently, but he does it way more. I know all about the nature of the small samples, but I can’t not be interested in swings of that magnitude.

Speaking of swings, we have to look. The following are against similar pitches in similar counts. First, 2014:

And, 2015:

As always, comparing individual swings carries a great margin of error. You don’t know if what you’re seeing is representative. But let’s just say. What might we observe here? Panik is clearly quick to the baseball. We already know he has to be, based on his contact rate. There’s a change in the behavior of the front foot — the second small step is gone, with Panik just lowering his heel. In the 2014 swing, Panik is more out over his front foot, while the more recent swing seems to be getting more from the back leg. And look at how Panik finishes. Previously, he cut himself off some. In the more recent swing, he turns his whole back to the camera. He finishes higher, having swung to get more loft. In short, it just looks like the 2015 version of Panik is a hitter who isn’t just content to put the ball in play.

I can’t speak to how representative those swings might be, but when you blend them with the numbers, you do get a certain picture. Sometimes, a hitter just isn’t strong enough to want to hit more fly balls. Billy Hamilton, for example, shouldn’t hit as many fly balls as he does. Ben Revere should try to keep the ball out of the air. A year ago, Panik looked like a guy who’d want to keep the ball on the ground or on a line, but now he has proof of some power upside. He shouldn’t get too fly-ball happy, but for him, a fly ball can be a hit. It can be the best of hits. With more strength in his swing, Panik is more like a hitter and less like a wall.

At the moment, the Giants have one of the best middle infields in baseball. Neither Crawford nor Panik were all that highly regarded, but they’re beating expectations and allowing the Giants to contend with what was supposed to be the league’s most terrifying juggernaut. Once upon a time, it seemed like the Giants were particularly good about developing pitchers. Now they’re having real success developing hitters. Maybe the Giants are just good at developing players.