SAN FRANCISCO (AP) — Buster Posey knows the day will come when he again has to step toward the third-base line, see a charging runner trying to score and brace for a collision.

That’s life as a catcher. Instincts take over and plays are made, or missed. Sometimes, such moments occur with devastating consequences, like Posey’s season-ending left leg and ankle injury last May 25 when he was run over at the plate by the Marlins’ Scott Cousins.

As new-look Miami visits AT&T Park on Tuesday for the club’s first trip back to San Francisco since that fateful day, Posey has surprised even himself with such a strong comeback. And anybody who understands the mindset of a catcher realizes just how hard it will be for Posey not to block the plate when the time comes, as Giants manager and former catcher Bruce Bochy has instructed since Day 1 of spring training.

“That’s something I really don’t think about,” Posey said of when he might be barreled over again. “It’s part of the game. I know there are going to be plays at the plate. The best thing for me to do is to make sure I’m in a good position. With the work that we put in this spring, it’s getting close to becoming second nature. Even last year, I never set up on the plate. I always set up a little bit in front of the plate, so it’s not that big of a change to move maybe a step out a little bit further.”

Catchers know it’s often an unavoidable collision course.

Astros catcher Jason Castro missed two games last week with a sore neck after a scary collision with the Brewers’ Mat Gamel.

On April 23 in Milwaukee, Castro was plowed over by Gamel, who wasn’t able to knock the ball loose and recorded the third out. Castro has said he won’t change his style on making such plays — using caution.

This spring, Bochy said he would take the decision of blocking the plate out of Posey’s hands because, “I certainly don’t want people to think he’s backing off on his own.”

The closest call Posey had in the opening month came when Mets pinch-runner Scott Hairston clipped the catcher’s leg to break up a double play attempt in the ninth inning of a 5-4 San Francisco loss at New York on April 21. Posey was knocked off balance and threw wildly to first trying for the second out, and the error allowed the Mets to score the winning run. Posey acknowledged Hairston’s play was clean.

“He’s doing fine. If you watch him, he’s not showing any effects,” Bochy said of Posey’s injury. “That’s behind us, that’s behind him and I really don’t think he thinks about it much anymore. You have a lot going on, but still your instincts take over there. Hopefully you’ve done enough practice where you’re going to do the right thing and get yourself in the right position. He did a lot of work in the spring.”

These days, Cousins is at Triple-A New Orleans and there’s more talk about outspoken Marlins manager Ozzie Guillen making headlines than what happened here almost a year ago. That’s largely to Posey’s credit. He has moved on, and shown signs he is still every bit the player he was before tearing three ligaments in his left ankle and breaking a bone in his lower leg.

The 2010 NL Rookie of the Year is batting .353 with four home runs and nine RBIs, has stayed on the field more regularly than he envisioned at this early stage, and has no lingering effects from the injuries. He has also made four starts at first base to give his body a break.

“I’ve been happy with the first month. My ankle has responded great,” Posey said. “I’ve been out there as much or maybe more than I hoped for. It stinks to be sidelined for any amount of time, but especially as long as I was last year. Just having fun each day and enjoying it.”

While Bochy told Posey not to block the plate, those who know the position realize that could be an awfully tough task when, in the heat of the moment, the only priority becomes stopping a run.

“I think you have to pick your spots,” said Oakland Athletics manager and former catcher Bob Melvin. “I think if you’re ahead 2-1 in the ninth inning and you have a base hit to center field with a man on second and it’s the difference in the game, my sense is, I don’t care who you are as a catcher, you have a chance to block the plate with the ball in time, you’re going to do what it takes to get the out.”

Some managers address preparing for such scenarios during spring training. Melvin said general manager Billy Beane has spoken to catcher Kurt Suzuki about it.

Padres manager Bud Black discusses with his catchers when to take the chance, and when they might be better off staying out of harm’s way.

Angels skipper Mike Scioscia, another former catcher, has been known to take it one step further with his club.

“What Mike does, and we do it a little bit in our spring training, he practices how to take a blow — about how you set your feet — but a lot of times you don’t have time to set your feet,” Black, a former Angels pitching coach, said while squatting down in the dugout to demonstrate. “He’ll get the catchers and they’ll have their gear on and he’ll have them get down in a certain position and he’ll push them, hit them, and they’ll have to roll over.”

Bochy has repeatedly voiced his strong beliefs that Major League Baseball should develop rules to better protect vulnerable catchers. The topic has been discussed at general manager meetings.

“It’s a subject that’s been exhausted, and there are a lot of people who have strong opinions about that, and some people in that room are catchers — ex-major league catchers, particularly Joe Torre. He was in there, and the opinions were vented,” Twins GM Terry Ryan said this spring. “There’s a certain way to take a guy out, there’s a certain way not to go after a guy. I think if you’re going to be a catcher, you have to be prepared to have a collision. It’s unfortunate what happened to Posey. No one wants to see that happen to anybody. But I think being a catcher, that’s part of the business.”

Posey knows that better than most, and he isn’t backing away from the crouching spot where he feels most at home: behind home plate.