It's no secret that Jose Altuve is having a rough stretch. After popping off for a .316/.361/.658 slash line after his first 19 games (in which he hit six home runs in five games), Altuve is 8x59 for a .136/.282/.254 slash line in his last 17 games. He has 15 out of 36 games with an 0-fer in 2019, after collecting zero hits a total of 30 times in 2018. His .237 batting average for the season is the lowest it's been since he was hitting .216 on April 11, 2017. This is bleak and it's certainly not the Jose Altuve to which we have grown accustomed. Good news is, he'll be fine.
BABIP
Jose Altuve's BABIP over the last 17 games is .140 and for the season he has a .225 Batting Average on Balls In Play. MLB as a whole has a .291 BABIP. So Altuve's luck in getting hits has temporarily evaporated. He has a career .338 BABIP, so this level of hitting into outs is unsustainable, particularly because...
Exit Velocity
I recently had a conversation with a friend who didn't buy in to the whole Exit Velocity thing. I explained as best I could: look, if you have a .200 batting average but you're hitting the ball 110mph off the bat, that's really bad luck. If you have a .400 batting average and you're hitting the ball 70mph off the bat, you're extremely lucky. Altuve's average Exit Velocity is currently 87.9mph, which is a career-high, and above the MLB average of 87.4mph. His power hasn't evaporated, which we know, but is further exemplified by...
Hard-Hit%
FanGraphs says Altuve has a 41.4% Hard-Hit Rate, meaning that he's hitting the ball hard 41.4% of the time, which is easily better than the 33.3% Hard-Hit rate he posted in 2018, and would beat his previous career high of 33.8% in 2016. Hitting the ball hard and not getting hits is incompatible. Let's compare it to 2018 when, you know, he had a broken kneecap:
Soft%, 2018: 16.6%
Soft%, 2019: 18.9%
Medium%, 2018: 50.1%
Medium%, 2019: 39.6%
Hard%, 2018: 33.3%
Hard%, 2019: 41.4%
That Soft% is in line with his 17.0% career Soft% rate. The difference is the balls he was hitting Medium-Hard (or his Chub%, if you will) are down while the Hard% is up. The hits will be there.
IFFB%
Altuve's percentage of infield fly balls is an insane 19.0%. That's 11th-highest out of 177 qualified hitter in 2019, so far. You have to go back to his 2011 Corpus Christi stint to find one remotely that high (17.5%) in his career. Keep in mind that Altuve's 41.4% Hard% is the 3rd-highest of hitters with at least a 19% IFFB% (Pujols and Moustakas are each hitting the ball hard 42.4% of the time, though Altuve's Soft% is the lowest of the three). For comparison, his IFFB% in 2018 was 5.9%. Altuve is getting under pitches and popping them up, something that someone with 1451 career hits should be able to rectify with time.
How he's getting pitched
According to Brooks Baseball, Altuve currently has "an exceptionally high likelihood to swing and miss" breaking pitches, to the tune of 46%. That's really high. Outside of four-seam fastballs (195 seen with a 6.15% whiff-rate) the pitch Altuve has seen most is the slider, at 110 times this season with a 20.91% whiff-rate. Wow you're right, Brooks, that is exceptionally high. It's higher than the 11.27% whiff-rate he had posted in his MLB career coming into 2019. I don't believe that Jose Altuve has just forgotten how to hit a slider.
Pull% vs. Center%
Altuve's timing is a little off. He has a career average of pulling the ball 41.1% of the time, this year he's pulling the ball 52.3% of the time. While he's going opposite-field at virtually the same clip from 2018 (19.8% in 2019, 20.0% in 2018), he's hitting the ball up the middle of the field 27.9% of the time, down from 38.6% in 2018. So those balls he was squaring up and dumping into center field are getting pulled instead.
Jose Altuve hasn't forgotten how to hit. It simply seems as though his timing is off lately. Power is still there, his knee seems fine, there are no underlying signs that his Hall of Fame career is in danger of cratering.