Mike Yastrzemski has a tight right calf

Mike Yastrzemski exited Thursday’s game against the San Francisco Giants and Seattle Mariners in the middle of the second inning. It wasn’t immediately known why Yastrzemski left the game, with even the broadcasters left in the dark. He didn’t appear to be in any pain, but when the bottom of the second inning rolled around, it was Luis Basabe in right field instead of Yaz.

Now we know why. The Giants announced that Yastrzemski left the game with a tight right calf.

The Giants are surely going to be careful with Yastrzemski, who has been the team’s most valuable player this season. So hopefully he left the game for precautionary reasons, rather than because he was dealing with a serious amount of pain.

There’s not really any time in the schedule for Yastrzemski to heal up. Thursday’s game was the second day of a string in which the Giants play 13 times in 12 days to finish the season.

They start a series on Friday against the Oakland A’s — a very good team — so the Giants surely have all their fingers crossed that Yastrzemski is good to go for that one.