The A's expect to know more in the coming days but will be cautious with Phegley, who underwent surgery July 5 to remove a cruciate ligament cyst from his right knee.
Phegley, who also missed two weeks in May because of discomfort in the same knee, has been limited to 26 games this season.
Gray nearing start of throwing program
Right-hander Sonny Gray (forearm) has not ruled out pitching again this season, an idea that might not seem so crazy given his recent progress. Melvin said Friday that Gray is potentially on the verge of beginning a throwing program within the next few days.
Gray would have to pass several tests throughout this process before the A's could consider pitching him in a Minor League rehab start, but the fact he's determined to even try showcases his commitment to finishing what's been a turbulent season with health on his side.
• Shortstop Marcus Semien was reinstated from the paternity leave list Friday, rejoining the team in St. Louis for the start of a six-game road trip.
Semien appeared in each of the A's first 124 games and had played in 126 consecutive games dating back to last season before missing Monday's contest for the birth of his first child, a son.
The infielder took the roster spot of left-hander Marc Rzepczynski, who was traded to Washington on Thursday.
• Designated hitter Billy Butler took part in all pregame baseball activities Friday, and he remains on track to return from the seven-day concussion disabled list Monday in Houston.
Jane Lee has covered the A's for MLB.com since 2010. Follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.