Coach Pete Carroll made the only choice he could realistically make after watching Russell Wilson dominate the Seattle Seahawks' quarterback competition.

He named Wilson the team's starter over Matt Flynn, not just for the final preseason game Thursday night, but for the regular-season opener at Arizona on Sept. 9. And he did so without any of the reservations that traditionally go along with starting a rookie.

"This is an extraordinary kid," Carroll said during a conference call Sunday night. "He just kept knocking us out with what he brought."

The decision came as the Seahawks were working to trade 2011 starter Tarvaris Jackson to Buffalo for a late-round pick. It also means free-agent addition Flynn will open the season as the Seahawks' No. 2 quarterback despite signing a three-year deal worth $19.5 million.

"Matt is disappointed," Carroll said. "Matt came here to be the starter. He took [the news] exactly the way a great competitor would. He still wants it. ... I’m disappointed for him, too, because I know how much he wants this."

Carroll made it clear from the beginning that there would be an open competition. Though reasonable in the beginning, assumptions that Flynn would start turned out to be as wrong as the assumptions typically made about players such as Wilson. A year ago, not even the unconventional Carroll could have envisioned going into an NFL season with a rookie starting quarterback standing 5-foot-10 and 5/8 inches.

This wasn't about Flynn in the end. It was all about Wilson emerging as a dynamic force in minicamps, training camp and the preseason. He won over the coaches right away with his hunger to learn and ability to handle more than what they threw his way. Wilson outperformed reasonable expectations at every step, most recently when he led Seattle's starting offense to six scores on its first six possessions against Kansas City.

Flynn, meanwhile, sat out the game with elbow soreness. While Carroll said Flynn's injury situation made the decision on Wilson clearer, the decision he announced Sunday night has seemed increasingly inevitable. Wilson has completed 67.3 percent of his passes with five touchdowns and one interception in the preseason. He has averaged 8.9 yards per attempt in addition to gaining 150 yards rushing.

"The more competitive situation we put him in, the better he was," Carroll said. "He just has a real knack for playing the game of football."

The Seahawks felt on draft day that Wilson possessed everything a top quarterback needed except for prototypical height. If any shorter quarterback could succeed, they thought, Wilson would be the one. They saw him excel behind a massive offensive line at Wisconsin. But when minicamps and training camp got going, Carroll said the staff was constantly looking for signs Wilson's height would be a limiting factor. They gave up eventually.

"So we just decided look at him as a quarterback and that's not even an issue," Carroll said. "The factor in his favor is, he is so elusive. He has rushed for 150 yards in preseason in limited time and always at the right time and effectively. It might not always be that way, but he has shown a great sense."

According to Carroll, Wilson had only four passes batted down at Wisconsin last season, all while operating behind that big line.

"We thought he was unique, his footwork and sense of spatial awareness and how he could handle that," Carroll said. "He has a great sense, he flows with the rush and finds passing lanes with an uncanny [knack]."

Whatever decision Carroll made was going to be a defining one for him. Naming Flynn the starter a few weeks ago would have been the safe move. It arguably would have been the smart move. But it wouldn't have fit with the competition mantra that has permeated Carroll's program at every level. Besides, Flynn was unproven as an alternative. Wilson won the job by a wide margin. There was no reason to pretend otherwise.