What happened: Bryce Harper responded to a proposal that Home Run Derby hitters swing aluminum bats once the contest's gold balls are in play, writing "Oh hell yeah. Let's go!" before adding his brain calls it "a terrible, dangerous idea." The idea originated from a suggestion floated in response to Harper's account.

Why it matters: The split reaction underscores the tension between spectacle and player safety that surrounds Home Run Derby gimmicks. This year's derby airs July 13 on Netflix, with MLB already promoting the event on its own channels.

What to watch: Watch whether MLB or derby organizers pick up the aluminum-bat suggestion before the July 13 event, and whether other players weigh in on the safety concerns Harper raised.