ANDERSON – Suddenly, size matters on the Indianapolis Colts’ defense.

For nearly a decade, the Colts had one of the fastest and smallest defenses in football, a perfect fit for Tony Dungy’s Tampa 2 system. New coach Chuck Pagano has brought in a different philosophy.

He ditched the traditional 4-3 alignment in favor of a 3-4 hybrid system that requires bigger defensive linemen and a new aggressive approach to force opponents into mistakes, and players like what they’re seeing.

“We brought in some guys and the first day I saw them, I was like ‘Gosh, how much do you weigh?’ I think they said like 330, 340, something like that,” cornerback Jerraud Powers said. “They probably have not had a D-tackle that big in a long time around here.”

The Colts (No. 32 in AP Pro32) needed a change after last season’s 2-14 disaster.

Indianapolis’ defense allowed 430 points, the fifth-highest total in the league and the fourth-most in franchise history. Opponents ran for a staggering 2,303 yards.

There were more problems defending the pass.

Opposing quarterbacks completed a league-record 71.2 percent of their attempts and piled up a mind-numbing rating of 103.2, the sixth-worst in NFL history. Even worse, Indianapolis and Minnesota tied for the league-low in interceptions (8).

For Colts’ fans who have long complained the defense was too small to stop the run, Sunday’s preseason opener against St. Louis will be a fresh start.

Pagano’s plan is to confuse the offense with schemes that remain relatively simple for the defense.

During the past four years in Baltimore, the Ravens relied on mammoth linemen, such as Haloti Ngata, to keep blockers off linebackers like Ray Lewis. Pagano’s star pupil was safety Ed Reed, the 2008 NFL Defensive Player of the Year. And when Pagano was promoted to defensive coordinator last year, Terrell Suggs won the top defensive award.

“Just watching the film, you see the way he gets after it,” safety Antoine Bethea said. “It’s more aggressive.”

Pagano and new general manager Ryan Grigson began reshaping the defense in March. Grigson unveiled the plan by quickly signing three free agents – safety Tom Zbikowski, the former Notre Dame star, 315-pound defensive end Cory Redding and 345-pound nose tackle Brandon McKinney – to help with the transition. All played with Baltimore last season.

Pagano then moved 245-pound defensive end Robert Mathis to outside linebacker and asked the other Pro Bowl end, 268-pound Dwight Freeney, to brush up on pass coverage so he can play linebacker, too.

Outside linebacker Kavell Conner will now play inside, and last week, Grigson traded cornerback Kevin Thomas to Philadelphia for linebackers Moise Fokou and Greg Lloyd.

Note: Rookie quarterback Andrew Luck was 30 of 45, with four touchdowns and no interceptions during team drills at Tuesday night’s practice. It was his most attempts at any practice during training camp.

Luck isn’t sure how much he’ll play in Sunday’s preseason opener, and he’s not lobbying for more time.

On Monday, offensive coordinator Bruce Arians told reporters Luck would likely play 20 to 25 plays against St. Louis on Sunday.

That’s comparable to the number of plays four-time MVP Peyton Manning got in his first preseason game when Arians was Indianapolis’ quarterbacks coach.