ANDERSON, Ind. — Robert Mathis had his choice of teams as a free agent this offseason. Dwight Freeney spent much of the late winter and early spring wondering if the only team he’s ever known still wanted him.

This afternoon both will be on the field at Anderson University as the Indianapolis Colts go through their first padded practice of 2012 training camp. They remain leaders for a defense many experts are counting out, but nearly everything else around them has changed.

New head coach Chuck Pagano arrived from the Baltimore Ravens in February, and he brought his version of the 3-4 defense with him. That means Freeney and Mathis no longer are considered defensive ends, the position they’ve played for a combined 19 years in the NFL.

“It’s just now I guess being labeled an outside linebacker, which I don’t know about that yet,” Freeney said after Monday’s morning walk-through.

“But whatever it is, it’s just a little bit different for everybody.”

How different?

Freeney remembers his first practice during organized team activities this spring when he got his initial look at the new defensive gameplan.

It was a far cry from the “Tampa 2” zone defenses the Colts had been running since Tony Dungy arrived as head coach in 2002.

“I will say the first day was rough, that was in May,” Freeney said.

“We’ve always been Cover 2, and that was all we knew. That first day I remember, that first package went in, and it was like 15 blitzes. I’m standing up, new terminology, and I had no idea what was going on. I was like a rookie. But being out there, being in the fire, I learned quickly.”

There was speculation Freeney would be a bad fit for this scheme. He carries a $19-million salary-cap number, and rumors quickly spread that he would be traded.

A fake tweet during the NFL draft in April even gained traction, announcing Freeney had been traded to the New England Patriots for a third-round pick.

None of the rumors proved to be true.

In fact, Pagano sees both Freeney and Mathis as cornerstones in his defensive plan. They have a combined total of 11 Pro Bowl selections and

186 sacks.

But most importantly in Pagano’s mind, neither player tried to throw his weight around and complain about the changes.

“It’s all about the ’shoe (on the helmet), and it’s all about your name,”

he said. “It takes a lifetime to build that up and you can make one bad decision, one bad choice and everything that you’ve done to kind of etch your legacy, those guys have done too much. They’ve got way too much pride and they’ve got way too much integrity to do that. So it didn’t shock me.”

They also share a healthy competitive nature that has them excited about the challenge ahead.

Mathis could have opted out. He could have signed with any team running a

4-3 scheme and carried on with his decorated career.

But he made no such move. He wants to help this franchise return to the perennial playoff contender it was from 2002-10, and he believes Pagano and his defense will help get the Colts there.

“You’ve got to buy in,” Mathis said. “You have to shift yourself out and buy in. I bought in all the way. I bought in after we went 2-14 (last year).”

It’s hard to say at this point just how much Mathis’ and Freeney’s roles will change. Freeney estimates he could still line up with his hand in the ground as often as 75 percent of the time, and he admits he isn’t ready to drop back in pass coverage against the NFL’s top receivers.

“I don’t think I’m ever going to be comfortable with covering (Colts

receiver) Reggie (Wayne),” he said. “I mean, I probably can cover Reggie about two yards. The first two steps, I got him. After that, it’s up to the blitz or whatever is going on.”

Pagano’s defense will play to the duo’s strength, and that means rushing the passer. But there’s plenty that must be done right before the defense can turn Mathis and Freeney loose.

“They fully understand that in order to do (rush the passer) we’ve got to get people into third and longs,” Pagano said. “So we’ve got to play great run defense on first and second (down) in run situations. They’ve adapted extremely well. Obviously, it’s all new to them. But putting the time in that they put in in the offseason is making this camp a heck of a lot easier for both of them. They both bought in hook, line and sinker and hats off to those guys. That’s just the kind of men that they are.”

The short sprint to the regular-season opener on Sept. 9 in Chicago begins today when the full pads come on for the afternoon practice. Mathis said he can’t wait to mix it up with the offense — “If you’ve got the ball, you’ve got to get hit.” — and he feels his teammates are ready for the same.

“Everybody is hungry and ready to hunt,” he said. “Everybody is having fun. You just have to get the grind out of the way, and that’s camp. So we’re going to do that, and then we’ll be on our way.”