Jon Hamm‘s ascent among Hollywood’s leading men via the buzz-rocket that is “Mad Men” begs the question: Where’s he been all these years?

Hiding in plain sight, that’s where. Much as George Clooney did in a slew of forgettable TV shows until he found the perfect match with NBC’s “ER.”

Hamm in recent years had been a semi-regular on CBS’ “The Unit,” and on ABC’s defunct “What About Brian?” and NBC’s “Providence.” He was a regular from 2002-04 on Lifetime’s police drama “The Division,” and he had a few low-profile movie roles in such pics as “Kissing Jessica Stein” and “We Were Soldiers.” Heck, he even played a cable guy on Comedy Central’s “The Sarah Silverman Show,” among other one-off TV guest shots.

Hamm may have lost the lead drama actor Emmy trophy to “Breaking Bad” star Bryan Cranston at the Emmys, but he is certainly one of the year’s big winners, as crix dig for superlatives to describe his work on “Mad Men.”

But his breakthrough role did not come easy. Hamm auditioned seven times for the role Don Draper, recalls Connie Tavel, the thesp’s manager for the past six years. Series creator-exec producer Matthew Weiner was sold on him the minute Hamm opened his mouth — and he was at least “No. 90” on the list of thesps who read for the role, Weiner has said — but it was still a long road to clinching the part.

Tavel, a veteran manager who reps the thesp along with percentery ICM, says Hamm’s pre-“Mad Men” career was marked by a series of near-misses. He was constantly up for lead TV roles but never made it all the way … until he landed his breakthrough gig.

“He would always come very close. Everyone always liked him, but he always came in second,” Tavel says. “Finally, he came in first in the perfect vehicle.”

Deborah Joy LeVine, creator and exec producer of “The Division,” calls Hamm “the sweetest guy on the planet.”

“I remember at his audition, I turned to someone and said, ‘Is he as good as I think he is?’ Where’s he been?,” LeVine recalls. “I’m only surprised it didn’t happen sooner for him.”