What happened: The Boston Red Sox are acquiring infielder Brett Harris from the Athletics. Harris had been designated for assignment by the A's three days before the deal came together. He now heads to Boston as an added infield option.

Why it matters: The move gives Boston low-cost infield depth without surrendering a significant piece of its core. For a Red Sox club balancing roster flexibility, adding a controllable infielder off the scrap heap is the kind of margin move that can pay off if injuries or slumps hit the position group.

What to watch: Watch whether Boston carries Harris on the active roster or assigns him to the minors, and how quickly he factors into the infield mix.