NEW YORK — Every escape act is slightly different, though for Yankees reliever David Robertson, the set-up always remains the same.

In the moments before he takes the stage, hearts have already started to pound because an opposing team has begun a rally, threatening to wipe away a slim Yankees lead. With trouble standing on every base, manager Joe Girardi emerges from the dugout, claps his hands together, and waits for the magic to happen.

“He’s been put in some of the biggest situations with runners on base and he’s done a great job,” fellow reliever Joba Chamberlain said. “It’s a huge thing.”

Nicknamed Houdini by his teammates, Robertson rarely disappoints with his signature trick, making base runners disappear. Just like the famous magician, Robertson plies his trade by creating illusions.

After all, nothing about Robertson suggests he’s capable of the extraordinary.

At first glance, his slight 5-foot-11-inch, 195-pound frame raises questions about how hard he could possibly throw, and for how long until he breaks down. His radar gun readings hardly wowed the scouts. He entered the 2006 draft after a distinguished career at Alabama, but the Yankees did not choose him until the 17th round.

Yet, he has become one of the most valuable relief pitchers in baseball.

Robertson’s 1-0 mark and 1.42 ERA hardly touches on the full extent of his value, which only surfaces when measured by how much he has raised his team’s chances of winning. In that regard, over the last two seasons, only Mariano Rivera has been more valuable to the Yankees out of the bullpen.

“He just has the ability to do that because he’s a strikeout guy,” Girardi said of Robertson, whose 14.21 strikeouts per nine innings is among the best in baseball. “He’s been a strikeout guy since he came up. And he just continues to do it for us.”

Yet, Robertson’s demeanor runs contrary to that of many relievers. Ask him if he’s ever comfortable in a close game, where just one mistake could lead to disaster, and Robertson quickly offers a correction. He concedes that perhaps he has gotten used to walking a tightrope without a net, but never gotten comfortable.

“You’re going to have adrenaline,” Robertson said. “When you get into a situation like that, you can’t stop it. The trick is to use it to your advantage, to calm it down so you just have a little bit more, because if you have too much going you’re just all over the place.”

His adrenaline was everywhere on the night he pulled off his first great escape — bases loaded, nobody out, 11th inning against the Twins in Game 2 of the 2009 Divisional Series. Robertson did not allow a run, the Yankees survived, and went on to win a World Series. Ever since, when it’s time to wriggle out of jam, Girardi’s first call has been Robertson.

“Sometimes, you can calm it down,” Robertson said. “Sometimes, you just can’t stop it.”

Of course, the contradictions are only part of the illusion.

Start with his fastball, the one long ago dismissed by those who view the radar gun as gospel. Sure, it may reach the plate at 92, yet he makes hitters look as if it’s coming in at 102.

Even on hitters’ counts, when they know the pitcher has no choice but to throw a fastball, Yankees top scout Billy Eppler said hitters often find themselves swinging late. The reactions don’t match up with the gun readings.

For years, scouts and opponents alike dipped into baseball’s great store of clichés to explain why the diminutive right-hander posted strikeout rates. Robertson, they said, fooled hitters with what they called “late life.”

Chamberlain, who plays catch with Robertson every day, has long noticed that Robertson’s throws often “stay true,” maintaining velocity all the way from release until it hits his mitt.

Recently, however, a part of his secret was revealed in a magazine article. Sports Illustrated published the results of Trackman, an experimental ball flight radar used last season at a handful of parks. The radar showed that Robertson strides so far off the mound that he takes seven feet off the distance between the pitching rubber and home plate, well above the average of 5 feet 10 inches.

For Robertson, the extra reach takes his 93 mph fastball and turns it into a 95 mph heater.

Presto, late life.

“It could have just caught me on just one good pitch or something,” Robertson said. “I can’t say that it makes sense to me because I feel like there are a lot of other guys that do the same thing. A lot of other guys have the same life on the ball.”

Yet, for all of his gifts of illusion, none of them would do much good without Robertson’s sense for dealing with tense moments. Though he often holds the fate of his team in his hands but rarely thinks of the consequences. He accepts that he will fail from time to time. And because of the nature of his job, his failures can be spectacular.

Teammates, however, marvel at Robertson’s ability to wipe the slate clean after one of these meltdowns.

Robertson brings some of that understated toughness with him to the mound. If he’s in a close game, it’s because the opposing team has seized the momentum. The Yankees want it back. When batters are eager to dig in and swing away, Robertson steps off the rubber, like a needle scratching a spinning record. When they want to step out of the box for a moment to collect themselves, Robertson stares in impatiently from the mound, ready to throw a pitch the instant he’s allowed.

“You can’t teach that,” Chamberlain said. “He’s able to dictate the pace. Obviously, with the bases loaded, there’s some kind of rhythm going for them. He takes the ball and he dictates the rhythm.”

What results is a noticeable change of tone. To chaos, he brings order, setting the stage for the real magic to begin.

Prepare to be amazed.

*****

MR. BAILOUT

It is possible to estimate how much each out is worth toward a team's chances to win each game. Each situation of every game is assigned a certain win probability. Reliever David Robertson has specialized at bailing the Yankees out of situations when they have the most to lose. A look at his work this season through a statistic called win probability added:

April 19 at Toronto

The Yankees led 4-3 in the sixth inning but starter A.J. Burnett walked Jayson Nix to load the bases with one out, lowering the Yankees' chances of winning to 43.5 percent.

Batter, Result, Win probability

Yunel Escobar, strikeout, 56.6 percent

Travis Snider, strikeout, 68.8 percent

May 10 vs. Royals

The Yankees led 3-1 in the seventh inning but starter Freddy Garcia allowed a single to Jeff Francoeur and walked Eric Hosmer, giving the Royals runners at first and second with nobody out, lowering the Yankees' chances of winning to 64.7 percent.



Batter, Result, Win probability

Mike Aviles, Fly out, 73.4 percent

Jeff Francouer, Steals third, 70.4 percent

Matt Treanor, Walk, 64.0 percent

Alcides Escobar, Strikeout, 75.5 percent

Chris Gets, Strikeout, 87.5 percent

May 17 at Tampa

The Yankees led 2-1 with one out in the sixth inning. But the Rays loaded the bases, lowering the Yankees' chances of winning the game to just 47.7 percent, even though they had the lead.

Batter, Result, Win probability

B.J. Upton, Strikeout, 58 percent

Casey Kotchman, Strikeout, 70.9 percent

For more Yankees coverage, follow Marc Carig on Twitter at twitter.com/ledger_yankees

Marc Carig: mcarig@starledger.com