Walsh was optioned to Triple-A Salt Lake on Saturday, Sam Blum of The Athletic reports.
Walsh has struggled mightily across 78 plate appearances this season, hitting just .119/.244/.224. As a result, he had lost a regular role against right-handed pitching and had started only two of the Angels' last nine games. He missed a significant part of the campaign with insomnia and migraines, but he'll look to regain his rhythm at the plate with Salt Lake.