Altuve, 30, is in the midst of an uncharacteristically poor season. He hit .224/.284/.322 (63 OPS+) with three home runs over his first 155 plate appearances. His underlying metrics weren't much better. His average exit velocity (86.3 mph) is down a full tick from last season. Meanwhile, he's expanding his zone and swinging and missing more often, a combination that has resulted in a higher, career-worst strikeout rate and a reduced walk rate.
While it would be convenient to credit Altuve's struggles to the Astros' inability to steal signs, it should be noted that independent analysis suggests he was one of the Houston hitters least likely to receive a "bang," getting it on less than three percent of the pitches he saw in 2017. (We'll concede that It's possible Altuve received a heads-up through some other means.)
As such, Altuve's struggles seem more attributable to other factors, like age- and injury-related decline, or the volatile nature of small samples. To illustrate that point, consider that he hit .266/.322/.380 over 87 plate appearances last May/June while missing time because of a hamstring injury.
The Astros sure hope Altuve's issues are tied to his knee, and that the time off has allowed him to make a full recovery. They entered Tuesday having lost 10 of their 14 games in September. The Astros are still in possession of the sixth seed in the American League, yet they have just a 1.5-game lead over the Mariners with a pivotal three-game set in Seattle looming next week.