Moutncastle, who is opening at Triple-A Norfolk, will see significant time at first base this season, Joe Trezza of MLB.com reports.
He hit .297/.341/.464 with 13 home runs and a 121 wRC+ in 102 games at Double-A last year, so the assignment to Triple-A makes sense. Mountcastle's defense (particularly his below-average throwing arm) has always been his biggest weakness, so the transition to first base also makes sense. He could reach the majors this summer.