Three hundred and 26 prospects were invited to this week's NFL Scouting Combine workouts in Indianapolis, and for the first time in more than 20 years, the Steelers won't routinely scratch many of them off their list before they see them.

The Steelers hired more than a new coach when they signed Mike Tomlin; they bought into a new philosophy on defense. No longer will they dismiss a player because he's a "4-3" tackle or end or outside linebacker.

The Steelers have played a 3-4 defense since Chuck Noll switched to it in the early 1980s. They will stick with it next season, but Tomlin has coached 4-3 defenses throughout his NFL career and wants everyone to keep an open mind toward possibly moving to that defense in the future.

That means Steelers scouts will look at those tackles who aren't built to play the nose but are more suited to play inside than at end. They can look at undersized ends and not necessarily see them as outside linebackers two years from now. They can look at smaller outside linebackers who play more like Jack Ham than Kevin Greene.

"It's actually encouraging because it opens up another avenue of players that maybe previously didn't quite fit," said Kevin Colbert, the Steelers' football operations director. "If we're going to get to a 4-3 defense, you can take a smaller defense tackle now and consider him, because there might be a crossover. We don't really know until this thing comes together."

Had Ham come along in the past 20 years, the Steelers probably would have ignored him. Ham thrived as an outside linebacker in the 4-3 Steel Curtain of the 1970s and made the Pro Football Hall of Fame. He would not be an ideal outside linebacker in a 3-4 defense in which he would be asked to rush the quarterback most of the time.

Consequently, the Steelers made a habit of drafting undersized defensive ends, having them serve a year or two as a backup apprentice at outside linebacker, and turning them into Pro Bowlers.

Some of the Steelers' best outside linebackers were undersized college defensive ends: Clark Haggans (fifth round, 2000), Joey Porter (third, 1999), Mike Vrabel (third, 1997), Carlos Emmons (seventh, 1996), Jason Gildon (third, 1994) and Jerroll Williams (fourth, 1989).

Not only will they continue to look for those types of players, they also will keep an open mind on those who better fit a 4-3 as well. It's possible the Steelers could stay a 3-4 defense, move to a 4-3 or play both, which is what the Baltimore Ravens do.

"The elite players defy scheme," Tomlin said. "Troy Polamalu's going to be an excellent safety regardless of what defensive scheme he's in. Casey Hampton's going to be a dominant interior defensive lineman, regardless of what scheme he's in. So the elite players defy scheme.

"We're not going to get enamored with that. What we're going to do is we're going to continue to shape our package to do what our players do and do well. It'll be a constant evolution."

The Steelers have players who could start in either scheme. Brett Keisel is quick enough to play end in either, and end Aaron Smith is big enough to play tackle next to Hampton in a 4-3 and quick enough to play end in either.

"We're a 3-4 team right now, obviously," Colbert said, "I think -- as coach has explained -- with the possibility of maybe some day evolving and doing different things within a 4-3 or a combination. I don't think anybody knows at this point.

It should make for a more intriguing Combine for the Steelers, followed in order by a more interesting free agency period that begins March 2, and then the draft in April.

"When coach talked about his plan for the defense," Colbert said, "it was always, 'I know what you have, we'll go from there and see where our players take us, basically.' I think that's the feeling we all have."