Maybe in this age of the pitcher, when even perfect games are becoming kind of commonplace, the quality start is hardly noticeable. After all, what are three earned runs or fewer in six or more innings compared to no runs, no hits, no errors in nine innings?

But for the Yankees, reaching “quality” cannot be overstated. Neither can the return of Andy Pettitte, who almost single-handedly has transformed the “quality” of the Yankees rotation.

The Yankees are 31-4 when they author a quality start. The .886 winning percentage is second best in the majors. The leader is Baltimore (28-3, .903), which helps explain, in part, why the Orioles are hanging tough in the AL East. The major league average, heading into yesterday’s games, was .676.

BOX SCORE

But the Yankees had just 13 quality starts in their first 35 games (before Pettitte’s arrival). Only the Twins (9) and Royals (10) had fewer in the AL, and they continue to have the fewest overall.

However, since Pettitte’s first start, on May 13, the Yankees have an AL-best 22 quality starts in 31 games. The distribution has been fantastic: Pettitte and CC Sabathia have five each, Hiroki Kuroda, Phil Hughes and Ivan Nova have four each.

Maybe it is just coincidence the whole rotation is doing better since Pettitte came back to town. But I think there is more to it than just happenstance.

An NL personnel head said Pettitte has a “calming veteran presence.” He projects confidence and serenity. Suddenly, Hughes, Kuroda and Nova aren’t feeling nearly as much weight trying to line up properly behind Sabathia.

For the converse, look at what has occurred with the Phillies since Roy Halladay went on the disabled list. Before his injury — even with Halladay struggling somewhat — the rotation was 19-16 with a 3.32 ERA. The starters are 5-9 with a 5.40 ERA since Halladay went on the DL, despite the continuing presence of Cole Hamels and Cliff Lee.

Since Pettitte’s arrival, the Yankees rotation has gone from problem to asset. Obviously, the rotation is supported by both a strong lineup and bullpen. But that works both ways. By holding opponents down, the starters have minimized the offense’s redundant problems in the clutch.

One major reason the pen continued to thrive even with Mariano Rivera and David Robertson on the DL was tied to how deep the starters were getting into games. Manager Joe Girardi, always an excellent manipulator of the pen, has been able to define relief roles and limit workloads, especially in individual games because he has needed to cover, in general, no more than 6-9 outs.

Last night, no reliever was needed as Sabathia hurled a complete game in a 6-2 victory over the Braves. It marked the 18th straight game in which a Yankees starter had worked at least six innings. That is not only the longest such streak in the majors this year, but, more impressive, was the longest by the Yankees since Aug. 21-Sept. 9, 1981, when the quintet of Ron Guidry, Tommy John, Rudy May, Rich Reuschel and Dave Righetti went 19 straight games with a starter going at least six innings.

The Yankees also have had a starter last at least five innings in 36 straight games. That is the longest by the Yankees since a 58-game streak that covered the final 47 games of 2002 and the first 11 of 2003. That rotation and this one share something in common:

Andy Pettitte.

HARDBALL QUIZ

Since his Yankees arrival in 2009, CC Sabathia has 78 quality starts. Only six pitchers had more. Name them. (Answer below.)

Soriano could earn some big bucks

NEW Yankees closer Rafael Soriano is pitching himself into an interesting possibility by thriving in Mariano Rivera’s absence. If Soriano continues in this manner, he will have to decide if it’s in his best interest to pick up his player option for $14 million in 2013 or declare free agency in search of a multi-year contract.

In general, long-term dollars for closers have plummeted. Soriano’s agent, Scott Boras, saw that last year when two of his clients, Ryan Madson and Francisco Rodriguez, received just one guaranteed year each for $8.5 million and $8 million, respectively. It is not helping that many closers have incurred long-term injuries, including Madson, who is out for the year. Nor does it help that one of the two closers given significant dollars in the offseason, Heath Bell (three years, $27 million) has pitched poorly for the Marlins.

However, the closer who received the most, Jonathan Papelbon (four years, $52 million) has pitched well for the Phillies after excelling in the toughest offensive division, the AL East, for the Red Sox. Soriano also has that AL East pedigree. He led the AL in saves (45) with the Rays in 2010 and now is thriving with the Yankees. More impressive to potential suitors might be how he is doing in replacing Rivera, who was thought to be irreplaceable.

In his first 15 games since being installed as closer, Soriano has a 1.35 ERA and 13 saves in 14 tries. Soriano also arrived with the reputation of having a prickly personality, which he did not dispel last year. But he has seemed much more comfortable and low-maintenance this season.

Some teams in need of closers will appreciate all of this if, indeed, it continues. Soriano might not get $14 million a year, but what if he, say, were offered three years at $30 million? It would probably be in his best interest to jump at that, especially if it looks as if Rivera would return in 2013. Because, in that scenario, Soriano would almost certainly go back to being a set-up man in his walk year and run the risk of not being as enticing to the rest of the sport.

Hughes applauds Martin’s hard work

RECENTLY, when I asked Phil Hughes what he liked about working with Russell Martin, he cited familiar stuff such as how athletic Martin is, which enables the catcher, for example, to move quickly and be one of the better blockers of pitches in the dirt.

But Hughes concentrated on an item that generally only he and his teammates can see.

“[Martin] doesn’t carry over offense to defense,” Hughes said. “In fact, our video room is right near the dugout and whenever you pass it, there are hitters in there looking at their at-bats or what the opposing pitcher is throwing. But often you will pass by and Russell is in there looking at how we pitched the three batters due up the next inning, trying to figure out the best way to attack them.”

HARDBALL QUIZ ANSWER

Felix Hernandez (89), Justin Verlander (83), Jered Weaver (83), Matt Cain (81), Roy Halladay (80), Dan Haren (79).