That's not the result of a media campaign or something propagated by staff or front office members, though the pitcher has some advocates in those areas. It's a prevalent thought in the Yankees' clubhouse.
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"He's been as important to us as anybody on our team," Mark Teixeira said recently. "The eighth inning is really, really important, as everyone knows, and David has come into so many men-on-base, bases-loaded situations, and he gets out of them every time."
Nick Swisher agreed.
"He's been so instrumental for us," he said. "You think about our last three guys [Rafael Soriano, Robertson and Mariano Rivera], you're talking about three closers. There's no doubt, D-Rob could be a closer on any team in the big leagues. He's one of those guys that kind of baffles guys."
Never more so than this year.
Robertson earned the name "Houdini" inside and outside the clubhouse in 2009 when he escaped a bases-loaded, none-out jam in the 11th inning of Game 2 of the ALDS against the Twins. He preserved a 3-3 tie in a game his team would win on Teixeira's homer in the bottom of the inning.
And Robertson's Houdini routine this season became, well, routine.
Robertson, 26, finished the regular season with 662/3 innings pitched and a 1.08 ERA, lowest among AL relievers and second-lowest in the majors. He allowed one run in 36 innings in 36 appearances on the road, including Tuesday at Tampa Bay, when he made his 70th appearance of the season and struck out his 100th batter (in 662/3 innings). At one point, Robertson struck out 10 straight batters with the bases loaded.
"Ridiculous," Swisher said.
Robertson knows, however, that the off-the-charts numbers could be forgotten if he doesn't continue that kind of performance in the postseason.
"You can have an amazing season and then not do well in the playoffs, and it hurts," he said. "It hurts bad."
He knows from experience.
Robertson had an uneven 2010, starting slowly -- a 5.46 ERA in the season's first half -- but finishing strong with a 2.27 ERA in the second half. He headed to the offseason with a bitter taste, however, after allowing Nelson Cruz's two-run homer in the fifth inning of the Yankees' season-ending 6-1 loss to the Rangers in Game 6 of the ALCS.
"Threw a fastball in, missed over the middle and he belted it out," Robertson said last week, remembering the moment clearly.
But like the best relievers -- Rivera, for example -- he quickly pushed it from his mind.
"I moved on from it," Robertson said. "What's there to think about when you're done? When you're done, you're done. It's just a matter of waiting till you get back there again."
It's easy to forget that Robertson started this season with an undefined role. Soriano was signed to a big offseason contract to be Rivera's setup man and Joba Chamberlain was the seventh-inning pitcher. But when Soriano and Chamberlain went to the disabled list within three weeks of each other, manager Joe Girardi inserted Robertson, who already was pitching well, into the setup role, and the righthander took off.
"He's attacking hitters, he's throwing strikes," Rivera said last week. "If you throw strikes and you're attacking, good things will happen."
Rivera, who ended the season with 44 saves and a 1.91 ERA and shows no signs of slowing, gave his seal of approval when asked if Robertson has the makeup of a closer.
"I would say so," Rivera said. "He has the ability to do it, so it's up to him. This year, look at this year's numbers. You go in there, you're throwing strikes, you get people out. Simple as that. That's what a closer's going to do."
What's allowed Robertson to flourish this season, Swisher and others have said, is a mid-90s fastball that often acts like a cutter -- yes, Rivera has worked with him on it -- and a vastly improved curveball. It's not unusual to see Robertson strike out the side on fastballs one night and on curveballs the next.
"The swings and misses," Teixeira said about what most stands out. "Bases loaded one out, you put a good swing on it, you get a fly ball that scores a run. I've always liked relievers that have that swing-and-miss pitch, and he's got two of them."