Per MLB.com (today's article)
The MLB situation: Boston’s biggest infield question mark is at first base following Triston Casas’ season-ending injury. The Red Sox generated plenty of intrigue by first working Kristian Campbell out there last Friday, and it appears the club is still batting around the idea of sliding him over instead of relying on other stopgap options like Abraham Toro, Nick Sogard and the currently injured Romy Gonzalez. That’d open up the clearest lane for Mayer, even with shortstop Trevor Story enduring a rough offensive and defensive season.
When a promotion could come: Unlike Anthony, there is a distinct path for Mayer to reach Boston soon. Alex Bregman departed Friday's contest early with right quad tightness, and with the Sox in win-now mode, they could turn to their No. 2 prospect at any time in the coming days-to-weeks, especially as he gets settled in at second.