While manager Bruce Bochy said following Monday's 4-1 victory that Posey was doing fine, the Giants planned to check in with him overnight and re-evaluate him Tuesday. They weren't going to take any chances with the 2012 NL MVP and 2010 Rookie of the Year.
"He's got some symptoms so we're being cautious," Bochy said. "We'll continue to monitor how he's doing and he'll stay there until we think he's ready to play. The biggest reason probably is the fact that he is a catcher. You just have to be really careful about these things."
The 0-1 fastball with two outs in the first inning sent the Gold Glove catcher immediately to the ground. Athletic trainer Dave Groeschner sprinted toward the plate and Bochy was right behind. Posey got up on his own but exited the game, with Nick Hundley entering to pinch run and stay in the game behind the plate.
Posey told reporters that he was able to drive home following the game and had no problems sleeping afterward. He said he had some lingering symptoms but declined to go into detail whether that included headaches or nausea.
"We just thought this was the smart move, especially being a catcher," Posey said. "When you're dealing with your head you have to use caution. It's different than a hip or a knee obviously. I feel like it's the right move."
Posey will be restricted from any baseball activities for the next few days while continuing to go through the concussion protocol. He could come off the disabled list as early as April 18 when the Giants begin a two-game series in Kansas City. Bochy noted that Posey could potentially be San Francisco's designated hitter against the Royals.
"We're going to try to get this thing cleared up and we'll get him back on the field as soon as we can," Bochy said.
Catcher Tim Federowicz had his contract purchased from Triple-A Sacramento to take Posey's spot, while right-hander Clayton Blackburn was designated for assignment.