Matthews was placed on the 10-day injured list on July 17 with a left knee sprain, which he sustained in the final game before the All-Star break. His move to the 60-day list rules out a return before mid-September.
Matthews is doing defensive drills and hitting in his rehab and has taken part in pregame work at Daikin Park on the Astros’ homestand. He has yet to run bases, however, a step that would precede his starting a minor-league rehab assignment.
In 82 games this season, Matthews has a .197/.250/.332 slash line and a 64 OPS-plus. Matthews made 30 starts in center field, 14 starts in left and 10 starts at second base before landing on the IL.
Ullola was recalled from Triple-A last Friday and made one appearance, throwing a scoreless inning with two strikeouts Tuesday against the Angels. He has a 4.50 ERA in four outings over three separate callups this year, with four hits allowed and nine strikeouts in six innings.