The Eagles went into the draft not thinking they could get Fletcher Cox.

The team had the Mississippi State defensive tackle rated as the best prospect at his position, and thought that he would go in the first six picks - a price they weren't willing to pay.

But he kept falling, and falling. And when he got close to enough to their spot, the Eagles made a move, traded with the Seattle Seahawks and snatched up the 6-foot-4, 298-pound Cox with the 12th overall pick.

To move up three spots from No. 15, the Eagles gave the Seahawks the 15th pick, their fourth-round pick and the best of their three sixth-round picks. Coach Andy Reid said that the Eagles went into the draft committed to not dealing away either of their two second-round picks or their third-round selection.

And they likely would have needed to part with one or maybe two of those if they wanted to jump into the top six or seven.

Instead they bided their time, got a little nervous when Carolina (No. 9) and Kansas City (No. 11) were on the clock, and when the Panthers took linebacker Luke Kuechly and the Chiefs took nose guard Dontari Poe, Eagles general manager Howie Roseman phoned the Seahawks.

"We had ourselves honed in on what we wanted to spend," Reid said. "And so, we weren't going to get as elaborate as some [teams] did. We had other people there that we liked if this didn't work out."

For the first time in some time, Reid took a player in the first round that many had him targeting and that many fans pleaded he would take. Reid, the theory goes, needs to bounce back from 2011's 8-8 season in his 14th year with the Eagles if he wants to see a 15th.

Getting Cox, many believe, will help him right away. Reid often looks long term. He may not have that luxury this year, and that may have led to the confluence of his and Eagles fan's win-now objectives in getting Cox.

"He's athletic ability - it jumped out at you," Reid said. "For a big man to move the way that he can move - that's rare."

Not only does Cox come with an SEC pedigree, but the thing that caught the Eagles' eye, especially Jim Washburn's, were his pass-rushing skills, his athletic ability and the way both will mesh in the defensive line coach's scheme up front.

Washburn likes his defensive tackles to get after the quarterback and cede run stopping responsibilities to the back seven in many cases.

"I've coached Fletcher Cox my whole life," Washburn said. "I've coached him a million times. I've been in his house hundreds of times. I've coached southern black kids my whole life. That's what my life's work has been. We hit it off."

"[The Eagles] play the same scheme they did" at Mississippi State, Cox said. "Attack front. You control your gap."

The 21-year old finished his junior season with 141/2 tackles for loss and five sacks. Reid said that Cox has the flexibility to play anywhere along the line - as a one- or three-technique defensive tackle or an end playing in Washburn's controversial wide nine.

Washburn fell in love with Cox from the get-go, he said. He traveled down to Starkville, Miss. and spent a day with the Yazoo City, Miss. native.

"He gets to be coached by the best defensive line coach in the NFL," Reid said. "They developed a relationship. Wash was able to go down and hang with him a complete day and work him out and take him out to eat."

Cox will join a defensive tackle rotation - if that's where he stays - that is already deep. Cullen Jenkins and Mike Patterson are the projected starters, but both are aging. Jenkins is 31. Patterson will be 29 at the start of the season. Antonio Dixon and Derek Landri give Washburn two run-stoppers off the bench.

Despite the depth, Cox should play right away.

"It's big," he said about playing right away. "I get in and I learn the defensive plays and I play at 100 miles an hour. And that's what I like to do. Not think it."

While Washburn and coordinator Juan Castillo get some youth on defense, Reid gets what many expect to be an impact player. He needs it. His drafts on defense have been mediocre at best. He has struck out a number of times on the defensive line.

Draft picks like Jerome McDougle, Brodrick Bunkley, Victor Abiamiri and Trevor Laws have come and gone without leaving an imprint. It hasn't been for a lack of Reid's trying. With Cox, Reid has now drafted a defensive linemen the last five times he's had one of the first 15 picks.

Corey Simon was picked 6th overall in 2000, McDougle 15th overall in 2003, Bunkley 14th overall in 2005 and the Eagles traded up to No. 13 to get defensive end Brandon Graham in 2010.

A lot is riding on Graham, who missed most of last season as he recovered from knee surgery. Perhaps Cox, with his flexibility, is the safety net in case Graham does not pan out.

The Eagles entered the draft with nine picks. They still have six even after giving Seattle the 114th and 172d overall picks. Along with their second and third round picks, the Eagles still have a fifth rounder, two sixth rounders and the seventh rounder that came Wednesday after the Eagles traded Asante Samuel to Atlanta.

Contact Jeff McLane at 215-854-4745, jmclane@phillynews.com or follow on Twitter @Jeff_McLane.