Purdue linebacker Ryan Kerrigan poses with his family after being selected by the Redskins with the 16th pick in the first round. (Jonathan Newton/The Washington Post)

Thank you, Mike Shanahan.

You finally did what you needed to do Thursday night as the coach and leader of the Washington Redskins, selecting Purdue outside linebacker Ryan Kerrigan in the first round of the NFL draft.

Focusing on defense — after trading down from the 10th overall pick to the 16th — was exactly the right approach to help a poor 3-4 defense with significant personnel problems in every position group.

After making so many questionable moves last season on the biggest issues facing the Redskins, you provided a glimpse of hope that maybe — just maybe — you do “get it” about defense after all. The offensive-minded coach in you realized the defense had to be addressed first in this draft.

Although it seemed clear because of the problems on defense, Shanahan still had a choice to make. There’s also a glaring hole at quarterback because both Shanahans, Mike and Kyle, Washington’s offensive coordinator, have irreconcilable differences with Donovan McNabb, whom the team is expected to trade.

But Mike Shanahan chose wisely.

“We felt we had more needs right now” than at quarterback, the head coach said Thursday night at Redskins Park.

All indications are that Kerrigan is capable of providing the type of immediate impact needed to quickly bolster the entire defense. Adding a young playmaker to rush the passer opposite outside linebacker Brian Orakpo was a sound decision on many levels.

With Orakpo and Kerrigan, the Redskins now have potential bookend stars. They have two young players capable of applying consistent pressure on quarterbacks from the edge, which is a very big deal in the 3-4 formation.

Orakpo (191 / 2 career sacks) has proved himself in two strong seasons in the NFL. Teaming Orakpo with Kerrigan just makes sense, especially considering the former Boilermakers standout made big things happen throughout his college career.

Credited with 14 forced fumbles, Kerrigan is tied for the all-time division I-A record. His 331 / 2 sacks ranked second on Purdue’s all-time list. Kerrigan also finished fifth in school history with 57 tackles for losses.

“We needed somebody opposite Rak on the other side to put some pressure,” Shanahan said. “Any time [opposing teams] can slide to a guy like Brian, you would like to have a dominant pass rusher on the other side. We feel like Ryan can do that — beat tight ends, beat backs, obviously beat tackles.”

Kerrigan’s production, however, was only part of the story. He also brings presence to a defense that often lacked a strong identity during the rough transition to the 3-4. Kerrigan is a tone-setter because he “plays extremely hard,” Shanahan said. “A lot of times, he does it on second effort.”

Trading back was Shanahan’s first impressive move of the night. The Redskins previously traded their third- and fourth-round picks in this draft in separate deals to acquire tackle Jammal Brown and McNabb (they also gave up a second-rounder in the 2010 draft for McNabb).

Shanahan was eager to pick up another high-round pick in an attempt to bolster the roster at several positions, and he found a willing partner in Jacksonville, which took Missouri quarterback Blaine Gabbert in the spot Washington vacated. For their assistance, the Redskins received the Jaguars’ second-round pick, the 49th overall. The Redskins now have two more picks in the top 50 (Nos. 41 and 49) in the three-day draft.

“We were happy to do what we did,” Shanahan said, “and pick up an extra pick and get Ryan on the football team.”

Obviously, the defense should have been Shanahan’s focus.

He had to make a major move to help defensive coordinator Jim Haslett, who had the toughest job on the coaching staff last season because of the lack of overall talent for the scheme change and the awful Albert Haynesworth situation. Shanahan ordered the major shift from Washington’s longstanding 4-3 front to an aggressive 3-4, but he didn’t provide Haslett with the pieces to make an effective transition.

Kerrigan is a big piece.

“All I’ve been taught to do is play hard to the whistle,” Kerrigan said in a conference call with reporters. “They say play until the whistle blows, and I really take that to heart.”

Washington suffered a historic collapse in its worst defensive performance since 1954. After having a top-10 defense eight times in 10 seasons between 2000 and 2009, the Redskins finished 31st out of 32 teams and were at the bottom of the league rankings for much of the season.

It isn’t only that the Redskins need more players who fit with the aggressive scheme Washington modeled after Pittsburgh’s successful 3-4 philosophy, though that was a big part of the problem.

The Redskins still need help on defense. They need huge, agile guys along the defensive line to draw and defeat double-teams. They also need help at cornerback.

Shanahan, however, finally got it started in picking Kerrigan. He started to lay the foundation to potentially begin building something special.

Not only for today, but also for the short- and long-term future of a franchise that too often has displayed shortsightedness while living in the moment. That’s how the best organizations in this league operate, and this is the time of year when they separate themselves from the pack.

So thanks again, Shanahan. Thanks for finally providing hope that Washington, with a strong start in this draft, could be on that road again.