SAN FRANCISCO -- Though Buster Posey felt OK by all accounts after being hit squarely on his batting helmet by a pitch from Arizona's Taijuan Walker in Monday's first inning, the Giants will continue to scrutinize their All-Star catcher closely over the next few days and make sure he has no concussion symptoms.
Posey left the game immediately and told NBC Sports Bay Area "I feel good" after the Giants' 4-1 victory over the D-backs. He will be re-evaluated Tuesday by Giants physicians and is unlikely to play against Arizona. Nick Hundley will handle San Francisco's catching duties full-time until Posey returns. Utility man Aaron Hill is San Francisco's emergency catcher.
Though Posey underwent concussion-related medical protocol, the Giants' experience with second baseman Joe Panik taught them never to assume anything. Panik was hit in the head by future teammate Matt Moore last June 18 and remained in the lineup but began to feel concussion-like symptoms 10 days later. Panik ultimately missed 23 games.
Giants manager Bruce Bochy pointed out that Posey's position makes him more vulnerable to head trauma, explaining the instant decision to remove him from the game.
"He's a catcher," Bochy said. "So now he's even more at risk if he's catching and he takes a foul tip."

The sound of Walker's 94 mph fastball striking Posey's helmet sickened all who heard it.
"It's one of the worst sounds you can hear in baseball," Bochy said.
"It didn't sound good; it didn't look good," Panik said. "You never want to see that happen."
Walker never meant for it to happen, though many of the fans filling AT&T Park for the Giants' home opener booed him throughout the rest of the afternoon.
"I was a little [shaken] after I hit Posey in the head," Walker said. "That's always scary. You never want to do that."
Before Walker batted in the third inning, he and Hundley peacefully exchanged words.
"I just went up to him and said, 'Make sure Posey knows -- if he's all right, tell him I'm sorry."