What happened: Boston had already acquired Curtis Mead before an injury put his season in jeopardy. Triston Casas and Marcelo Mayer are now central to the club's keep-or-deal calculus.

Why it matters: The injury weakens the immediate return on Boston's first deadline deal and increases the need for another bat. Trading Casas or Mayer would reshape the infield beyond this season.

What to watch: Watch whether Boston makes Casas or Mayer available before the Aug. 3 deadline and whether Mead's injury prompts another acquisition.