PITTSBURGH — The steady stream of bold-faced names out the door has finally slowed.

Troy Polamalu. Ike Taylor. Brett Keisel. All three part of a defensive core that led the Pittsburgh Steelers to two Super Bowl wins and an appearance in another.

All three now retired or cut.

Throw in the departure of cornerback Brice McCain and the startling decision by linebacker Jason Worilds to call it a career at age 27 and another typically light-spending approach to free agency and it seems pretty obvious what the defending AFC North champions need to focus on in this week’s draft.

It’s just not obvious to the Steelers. Sure there are glaring needs in the secondary and at outside linebacker. Yet the franchise long ago abandoned the idea of treating its roster like some kind of economics class, where supply and demand are in a perpetual battle for equilibrium.

Besides, general manager Kevin Colbert figures asking a college kid to take over for somebody such as Polamalu — who stepped away earlier this month after a dozen often spectacular seasons — is an exercise in foolishness.

“You’re wasting your time trying to replace a guy like that,” Colbert said before adding that Polamalu is a “once in a lifetime” player.

Pittsburgh doesn’t need a once-in-a-generational talent so much as a sea of healthy, capable bodies to fit into their revamped 3-4 defense, a unit that figures to feature some new tweaks by recently promoted coordinator Keith Butler.

They could use an outside linebacker to pair opposite Jarvis Jones. A physical cornerback to pick up where Taylor left off would be nice.

Still, Colbert and coach Mike Tomlin aren’t going to head into Thursday night’s first round with a gameplan. Considering all the variables at play, it’s kind of useless.