He’s listed at a generous 5-foot-6, and he’s never hit more than 15 homers, so when you look up and see that Jose Altuve has hit five home runs already this year, you really just want to shrug and sing a song of sample size. But if you’ve been watching for longer, you’ll have noticed that this has been a long time coming, and that under the hood we find reasons to believe that this young man is just growing into his power stroke.

Last year, Altuve added a leg kick that improved his ability to leverage his frame into more power. “I’m hitting the ball harder, not as many singles, more power,” he told me last year when we talked about the change. Starting the process earlier with a leg kick also helped him recognize pitches earlier, which helped keep his strikeout rate down even as he hit for more power.

A quick look at what the change has looked like for Altuve. First, his swing in 2012:

And then again in 2015:

Another part of hitting for power is lifting the ball. Altuve has quietly increased his fly-ball percentage every year he’s been in the big leagues. Watch his ground-ball rate (in green) take that dive:

In more new-fangled language, he’s upped his launch angle over time, and he’s continued that process this year. He’s already moved his launch angle from 9.2 degrees on average last year to 10.8 so far this year. And the percentage of his balls in play in the ideal home-run range (25-30 degrees) plus ideal line-drive range (10-25 degrees) has increased from 28% last year to 40% this year.

And the rest of the picture is how hard he’s hitting the ball. Not only is Altuve ninth in baseball in exit velocity, he’s improved more than anyone. Here are the players who’ve recorded at least 30 balls in play this year — significant because exit velocity stabilizes around 40-50 balls in play — and improved their exit velocity the most over last year.

Because Altuve has a long history of lesser power, the projections have him falling behind the league-average power that he showed last year. But, given what we know about exit velocities and launch angles generally — and Altuve’s exit velocities and launch angles specifically — it’s probably more reasonable to expect something that starts with last year’s power as a baseline. And if you do that, you’ll find that it’s more likely that Altuve hits 20 home runs this year than 16.

And if Altuve does that, he’ll likely become the sixth person since 2000 — joining Hanley Ramirez, Mike Trout, Eric Byrnes, and Carlos Beltran — to record 20 homers and 40 stolen bases in the same season. And if he does all of that, Altuve will become only the second player (besides Jimmy Rollins, who managed it in 2007) since 1980 to record a 20/40 season at a listed height of 5-foot-7 or less.

He’d also zoom to the top of another leaderboard, hitting the eighth-most home runs for a hitter 5-foot-8 or shorter, behind Rollins (four times), Ray Durham, Dustin Pedroia, and Marcus Giles.

Yeah, you can call him a power hitter.