Mills (1-0) was effective in his Angels debut, controlling the Orioles on three hits over five scoreless frames.
Called up from Class AAA Salt Lake to make a spot start in the last game before the all-star break, Mills responded with six strikeouts and didn't issue a walk.
Baltimore's Wei-Yin Chen (7-5), meanwhile, lost for the third time in four starts, surrendering five runs on five hits through four full innings.
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