Gregor Blanco's difficulties with head injuries continue to plague him and might keep him from playing in another game in 2015.

The San Francisco Giants outfielder was diagnosed Friday with a concussion and could miss the rest of the season.

"He complained after the game in Arizona," manager Bruce Bochy said. "He thinks it's from a slide in L.A. when his head hit the knee of the infielder. It seemed to get worse."

Blanco had a stint on the seven-day concussion disabled list in June after being hit on the head by a throw from Brandon Belt during warm-ups.

Blanco is batting .291 with five home runs and 13 stolen bases in 115 games.

Information from The Associated Press was used in this report.