Rookie catcher Buster Posey blooms for the Giants

Bengie Molina hit a home run Wednesday in his team’s playoff opener. He had three hits in all, drove in two runs and caught a six-hitter.

That would be the kind of performance you would entrust a veteran catcher to deliver in October, particularly one with a World Series championship ring.

But Molina delivered for the Texas Rangers, not the San Francisco Giants. And the Giants, who dumped Molina three months ago, could not be happier.

The Giants are happy for Molina, to be sure, and they would love to see him in the World Series. Yet they are ecstatic over their rookie catcher, Buster Posey, who is expected to fill the cleanup spot Thursday when San Francisco plays host to the Atlanta Braves in a National League division series opener.

“We’re here because of the job he did behind the plate,” Giants Manager Bruce Bochy said, “as much as his hitting.”

The Giants live and die by their pitching staff, and entrusting it to a rookie — no matter how talented — carried some degree of risk.

“Those guys deserve all the credit,” Posey said. “They made my job easy.”

The Giants were 30-27 without Posey in the starting lineup, 62-43 with him. He had to master a variety of styles, from Tim Lincecum’s odd delivery and Matt Cain’s power repertoire to a trio of left-handers that get progressively softer, from Jonathan Sanchez to Madison Bumgarner to Barry Zito.

“It is pretty impressive, with the kind of arms we have on this team, for a young catcher to be able to handle this kind of diversified arms,” Giants reliever Jeremy Affeldt said. “You won’t see that come along very often.”

As a rookie batting in the cleanup spot on a playoff lineup, Posey is in rare company that includes Albert Pujols, Miguel Cabrera and Evan Longoria.

The last team to advance to the World Series with a rookie catcher: Yadier Molina and the St. Louis Cardinals, in 2004.

This division series features the two leading candidates for NL rookie of the year, Posey and Atlanta outfielder Jason Heyward, who played against each another in the Georgia high school baseball championships five years ago.

Heyward homered and drove in four runs on opening day. Posey did not arrive in San Francisco until May 29, playing mostly first base until July 1, when the Giants cleared the catcher’s spot for him by trading Molina to Texas for surplus reliever Chris Ray.

Heyward, 21, batted .277 with 18 home runs and 72 runs batted in. Posey, 23, spotted Heyward two months and batted .305 with 18 home runs and 67 RBIs.

He has a fan in Molina.

“To be honest with you, I love the kid,” Molina said. “He’s a great person. He’s very humble, very talented. Believe me, he’s going to be one of the big names in the league for many years. I’ll be very happy watching him from home knowing that I helped him out.

“He’s done an amazing job to get those guys pitching the way they are, and from my experience, that is not easy. The way he took charge was amazing. The kid is something special.”

bill.shaikin@latimes.com

Times staff writer Mike DiGiovanna contributed to this report from Arlington, Texas.