On April 8 Astros manager Bo Porter pulled J.D. Martinez from the game after a fourth-inning at-bat. Afterward neither Porter nor Martinez divulged the intricacies of the yanking, though Martinez did offer a hint, according to Brian T. Smith of the Houston Chronicle:
What did Martinez do? Nothing obvious stood out in reviewing the play; no hustle-related injustice or anything of the sort. Yet by the time Martinez returned to the dugout Porter was signaling for someone on the bench. So what sparked this whole thing? Here's a guess: Martinez broke a team rule by making the second of back-to-back first-pitch outs. (Chris Carter, who batted before Martinez, had also popped up on the first pitch.)
After digging through the gamelogs I found that Houston hasn't made back-to-back first-pitch outs at any other time this season. They have had other instances where consecutive batters put the first pitch into play, however, at least one of those at-bats resulted in a hit in each occasion. To compare them to two other randomly selected AL teams: Seattle has zero back-to-back first-pitch outs this season, and Kansas City has two.
If the Astros do have a rule like this then it comes close to the minor-league rule some teams install that mandates batters to take until they get a strike. (For what it's worth, the Astros put the ball in play about as often on the first pitch as the rest of the league does; 10.1 percent for Houston, 10.7 percent for the league.) With Martinez saying he doesn't want his teammates to believe he's selfish he's implying that there's either a rule or a heavily suggested understanding in the clubhouse that batters will be aware of others' at-bats and not make quick outs.
That or Martinez did something out of sight to everyone but Porter.