O'Neill signed a three-year, $49.5 million contract with the Orioles on Saturday, Jon Heyman of the New York Post reports.
O'Neill is out of the Red Sox's lineup Sunday against the Rays, Christopher Smith of MassLive.com reports.
O'Neill is not in the lineup for Friday's game against the Rays, Chris Cotillo of MassLive.com reports.
O'Neill is absent from the lineup in Tuesday's game versus the Blue Jays, Jen McCaffrey of The Athletic reports.
O'Neill (back) will start at designated hitter and bat fourth in Monday's game versus the Blue Jays.
O'Neill (back) is out of the lineup for the second game of Sunday's doubleheader with the Twins, Mac Cerullo of the Boston Herald reports.
Red Sox manager Alex Cora said Sunday that O'Neill is dealing with some minor back tightness, Mac Cerullo of the Boston Herald reports.
O'Neill is not in the lineup for the first game of Sunday's doubleheader against the Twins, Mac Cerullo of the Boston Herald reports.
O'Neill is out of the lineup for Saturday's game against Minnesota, Jen McCaffrey of The Athletic reports.
O'Neill is not in the lineup for Sunday's game against the Tigers, Christopher Smith of MassLive.com reports.