NEW YORK -- For the fifth straight game Wednesday, Jose Molina was the Yankees' catcher. Or, put differently, for the fifth straight game, Jorge Posada wasn't the Yankees' catcher.

Posada said his right (throwing) shoulder, in which he had rotator cuff tendinitis that forced him to miss 16 games earlier this season, is fine, although surgery is possible after the season.

Manager Joe Girardi said the decision to start Molina is mostly based on the opposing pitchers and the fact that Posada is still building arm strength, though Posada said his shoulder is "as good as it's going to get."

Meanwhile, Molina is likely to catch starter Mike Mussina for the Yankees, as he usually does, against the Pirates on Thursday. And as Molina's appearance behind the plate has gotten more common, so is the sight of him throwing out runners attempting to steal a base.

Before Tampa Bay's B.J. Upton stole second base in the seventh inning Tuesday, Molina had caught 12 straight runners, the longest streak in baseball since 1993. Although Molina's hitting just .231, his defense has been superb in his 47 games started behind the plate this season. He's thrown out 23 potential basestealers and has a 46.9 percent success rate -- both marks are tops in baseball.

"Sometimes I don't know how I do it," said Molina, a nine-year veteran who's never started more than 79 games in a season. "It just happens, and I don't even look at the tapes."

With throwing out runners, much, if not all, comes down to the throw from the pitcher. One that's off-target or slow lowers a catcher's chance of nailing the runner. What does help, though, is having a quick release, which Molina has, according to Chad Moeller, the third catcher on the Yankees' roster.

"He's amazing to watch every day, especially when it comes to throwing," Moeller said. "Good arm strength, and he can throw the ball so lightning fast. It looks like it barely touches glove and it's already on its way."

Added Molina: "It's a reaction, too. A lot of things have to come together. The pitcher holding the runner and a good throw."

Girardi will continue to decide who starts at catcher on a day-by-day basis, and he prefers Molina when the Yankees play a club like the Rays, whose 100 stolen bases are the most in the Majors.

Said Girardi, "I know [Molina's] played very well, and he's done an exceptional job back there and he's been important to our club."

Pitching matchup
NYY: RHP Mike Mussina (11-6, 3.64 ERA)
Mussina picked up his 11th win of the season in his last start against the Red Sox on Saturday. The veteran right-hander tossed six shutout innings, allowing just four hits and striking out five.

PIT: LHP Paul Maholm (5-5, 4.05 ERA)
Maholm continues to be the stabilizer in the rotation. With another stellar outing his last time out, the lefty has gone at least eight innings in four of his starts this season. No other Pittsburgh starter has done so once. Maholm has revamped his preparation routine, and it's led to a much-improved efficiency and a tendency to stay lower in the zone with his pitches. When he's getting ground-ball outs, it's a sign that all is right. Maholm was the pitcher in the game which was rained out back in June. The lefty had allowed three runs on five hits in 2 2/3 innings before the game was postponed.

Tidbits
In Wednesday's win against the Rays, Bobby Abreu became the fifth Yankee to collect a walk-off hit this season. ... New York is 21-10 in series finales this season. ... The Yankees are 10-4 in one-run games at home in 2008. ... Reliever Brian Bruney made his third rehab appearance Wednesday, throwing one scoreless inning for the Gulf Coast League Yankees in Tampa, Fla.

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Up next
• Friday: Yankees (Joba Chamberlain, 2-2, 2.45) at Blue Jays (Jesse Litsch, 8-5, 4.01), 7:07 p.m. ET
• Saturday: Yankees (TBD) at Blue Jays (John Parrish, 1-0, 1.50), 1:07 p.m. ET
• Sunday: Yankees (Andy Pettitte, 10-6, 3.93) at Blue Jays (Dustin McGowan, 6-7, 4.37), 1:07 p.m. ET