his is bad news for an organization light on good hitting prospects.

Outfielder Mac Williamson, who hit 25 home runs for Class A San Jose last year, apparently has an injury to his right ulnar-collateral ligament and is being evaluated for a possible Tommy John reconstruction surgery.

Williamson, 23, has been dealing with the injury to his throwing elbow all season. Even though he had been ticketed for promotion to Double-A Richmond, Va., he started the season with San Jose because he could exclusively be a designated hitter there. Pitchers hit in the National League parks in the Eastern League.

The Wake Forest alum hit .318 with three home runs for San Jose this month before he was placed on the disabled list late last week.

If surgery is required, the recovery process typically does not take as long as it would for a pitcher. Outfielder Carl Crawford had Tommy John surgery in August, 2012, when he played for Boston, but he made the Dodgers’ Opening Day roster the following season, less than eight months after the operation.

Williamson is a rarity in the Giants’ system, an outfielder with power. The Giants selected the 6-foot-5, 240-pound right-handed hitter with their third-round pick in the 2012 draft.