INDIANAPOLIS (AP) - Indianapolis' bruised defense finally got some help Sunday.

Four days after team owner Jim Irsay ignited speculation about a possible trade with a series of Twitter posts, the Colts acquired former first-round draft pick Vontae Davis to solidify their secondary.

Miami will get Indy's second-round pick and a conditional, undisclosed late-round pick in the 2013 draft - a steep price for a veteran cornerback who recently lost his starting job, but one the Colts found reasonable.

I think if Vontae were coming out in the 2013 draft, there's no way he'd be there. A guy of this caliber and with this talent level and skill set, he wouldn't be there in the second (round),'' Colts coach Chuck Pagano said.You don't find guys like this in the second.''

The addition of Davis came hours after the Colts took another big defensive hit when an MRI confirmed defensive tackle Brandon McKinney injured the anterior cruciate ligament in his left knee. Pagano said McKinney would likely go on injured reserve soon, ending his season.

McKinney, one of several ex-Ravens now in Indianapolis (No. 32 in AP Pro32), was signed as a free agent in April to add size and depth to the defensive line. With his knowledge of the Ravens' defensive system, Pagano and the new Colts coaches expected him to help Indy make a smooth transition from their traditional 4-3 defensive front to Pagano's preferred 3-4 hybrid.

It's been that kind of preseason for the Colts, who have lost two backup linebackers with season-ending knee injuries and will be without starting inside linebacker Pat Angerer (fractured foot) for several more weeks.

The Colts also played Saturday without new defensive end Cory Redding (knee) or linebacker Robert Mathis (shoulder) and have now lost the 345-pound McKinney in the middle of the defensive line.

``Losing the couple of linebackers that we've lost and now Brandon and the injuries that have kept some guys out for a couple weeks here and there, it's tough from a continuity standpoint,'' Pagano said.

``You'd love to have them all playing together just from a communication standpoint and a trust standpoint and all those types of things. So it's been a challenge for Greg Manusky and our defensive coaches. ... It seems like every time we come out of a preseason game or what not, we're adding somebody new to the mix.''

Davis is the newest addition and will fill a huge void.

Jerraud Powers has been a solid starter at one cornerback spot each of the past three seasons and was expected to do the same again this year.

But with no clear winner in the competition for the other spot, new general manager Ryan Grigson began talking with the Dolphins about Davis.

The No. 25 overall pick in the 2009 draft was a starter since his rookie season, but his effort and conditioning were questioned during this summer's training camp and he lost his starting job to newcomer Richard Marshall.

Sean Smith is the other cornerback for the Dolphins (No. 27 in the AP Pro32), who have endured three consecutive losing seasons and are rebuilding under first-year coach Joe Philbin. That made Davis expendable, and the Colts approached Miami general manager Jeff Ireland about a deal.

My job is to try to establish a strong foundation of success, and build on that moving forward,'' Ireland said.We want to be a good team not only this year but in coming years. This helps us achieve that objective. We're in a stronger position today to reach our goal of building a team that will continue to perform at a high level over a sustained period of time.''

Ireland said he agreed to the trade in part because he's pleased with the development of several youngsters in the secondary, the biggest question mark regarding the Dolphins' defense.

``I have a lot of confidence in our defensive backs,'' he said.

Apparently, Davis appreciates the chance to start over in the Midwest, only a two to three-hour drive from his alma mater - Illinois.

``Thank GOD for keeping me in the right direction!!!!!'' he wrote on Twitter.

In 44 career games with Miami, Davis had 148 career tackles and nine interceptions.

In Indianapolis, he'll get a chance to strengthen a revamped secondary that managed to avoid another potentially devastating blow when Powers motioned to the coaching staff that he needed to come out during Washington's second series.

Trainers diagnosed the injury as a sprained knee, and an MRI confirmed the diagnosis Sunday.

Pagano said Powers would be listed as day to day with a ``mild'' sprain and that he probably would have returned to action had it been a regular-season game.

By pairing Davis and Powers, the Colts now have two established starters at cornerback and a bevy of youngsters vying for playing time behind them.

That group includes Josh Gordy, D.J. Johnson and Cassius Vaughn - all NFL veterans Indy has acquired in trades this year - and Justin King, another NFL veteran who signed with Indy as a free agent.

Vontae brings a great skill set, a great cover man, he's big, he's physical and he can run,'' Pagano said.Just throwing him into the mix, we feel we are getting an outstanding player that has proven himself and played at a high level in the league, and obviously will make us better moving forward.''

Pagano also said Sunday that undrafted rookie Griff Whalen, one of Andrew Luck's teammates at Stanford last season, would be out indefinitely after fracturing his right foot Saturday. Whalen missed the start of training camp with an injury to the same foot.

AP Sports Writer Steven Wine in Miami also contributed to this report.

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