According to Adam Rubin of ESPN,
Bay said he originally tweaked his hamstring Saturday, when he stepped on Ryan Howard‘s foot while running to first base during a victory over the Philadelphia Phillies.
Bay was lifted in the fourth inning of last night’s win.
After the game, Bay told the NY Post
“Terry was aware of it,” Bay said. “I kind of felt it was OK if I was jogging. I hit that ground ball to short and my first couple [of] steps, I could feel it. I kind of slowed down but there was something that kind of prevented me from really going and then there was a ball down the line my first couple steps again your first instinct is to go real quick, but I could feel it immediately. Not bad, but enough that I’m a little concerned that if I keep going at that pace something bad might happen.”
What else bad can happen to his season at this point?