Phillips was optioned to Triple-A Norfolk on Sunday, Rich Dubroff of BaltimoreBaseball.com reports.
Phillips didn't allow a run through eight Grapefruit League appearances (9.2 innings), racking up a 10:3 K:BB in the process. Still, the Orioles want the right-hander to spend more time in the minors after struggling to a 13.11 ERA in his big-league debut last season (11.2 innings).