In the seventh inning of the Giants' 13-8 win over the Padres on Thursday, Will Middlebrooks hit a ball to the wall in straightaway center field, which Pagan had in his glove. But as Pagan made contact with the green padding, the ball popped out.
The outfielder limped around the grass after he threw the ball back into the infield, but was able to stay in the game. Friday, however, Giants manager Bruce Bochy was forced to pull Pagan from the lineup.
"We really didn't know too much until this afternoon," Bochy said Friday.
Pagan met Friday with team doctors who determined there to be no structural damage. Bochy said Pagan is dealing with some swelling and is "doubtful" to play Saturday, but believes it could be a few days before he returns.
"We'll see how he's doing [Saturday]," Bochy said.
The team will likely be without all three of its starting outfielders for the next couple days, with Nori Aoki and Hunter Pence on the DL.
"If you look at our depth in the outfield, it's a little thin right now," Bochy said.
Pagan is off to a disappointing start to the season. He has yet to hit a ball out of the park and his WAR is -0.3, according to Baseball Reference. His .305 on-base percentage and .330 slugging percentage would both be career lows if they hold through the season.
The Puerto Rican outfielder has dealt with numerous injuries in his 10-year career and hasn't played in 100 games since 2012 when he appeared in a career-high 154.
• Matt Cain threw 98 pitches for Triple-A Sacramento on Thursday night. The right-hander completed 5 2/3 innings and allowed two runs on four hits while striking out four.
The three-time All-Star is on track to return to the rotation sometime next week, Bochy said. Cain said he feels good and is eager to return to the team.
"It's been a long time," Cain said. "A lot of working out, rehabbing, watching and not being able to participate. It'll be good to feel like you can contribute some."