Steven Threet has a lingering headache. Sunglasses are a constant companion. It's been this way for six months.

The former Arizona State quarterback still hasn't seen the hit that ended his career last November against UCLA. He hears it doesn't look bad on film. That's how it works with athletes who suffer repeated brain trauma.

Log enough concussions, and the slightest crack can spell the end.

"They always ask you, 'On a scale of 1-10, how does it feel?' " Threet said of his headaches. "Usually it's a 3 or a 4. But the first couple of months, a lot of times it was going up to 8's and 9's."

Threet is an intelligent young man. Like his doctors, he saw the ominous trend in his own career and across all levels of football. His two-time experience as a transfer student schooled him to make objective, unemotional decisions. He walked away from the game in February to save his brain, and just like that, Brock Osweiler was ASU's quarterback by default.

Yet it all happened so quickly. While his teammates crammed for the season-ending game against rival Arizona, Threet rested in a dark room, waiting for the symptoms to subside. Most nights, his head pounded so hard he couldn't sleep.

Like countless other football players, Threet never worried about concussions in the past. The first three were annoyances, and each time, he was back on the field for the following game. In his mind, concussions required less sacrifice than the injections he took to play with a separated shoulder.

But over Christmas break, while resting on a couch back home in Michigan, Threet had an epiphany.

"Mom," he said. "I don't know what's going on, but my head still hurts from that concussion I got at UCLA."

Maternal alarm bells ensued, and Threet was soon announcing his retirement from Division I football.

From his perspective, Threet merely exercised good judgment. He wanted to try his hand at a professional career, but has other interests. He studies finance and invests in the stock market. He wants to open up clothing stores. And when the doctors told him another bad concussion could scramble the eggs forever, well, it was time for self-preservation.

Yet Threet is part of a larger story. He represents a new breed of football player armed with a great amount of medical information, cognizant of his health and unwilling to risk everything for a few moments of athletic glory. Forty years from now, he will look back in relief, comforted that he got out in time.

At least that's the hope.

"For me, I'm no longer Steven Threet, the player," he said. "I'm the next stage."

Still, it's hard to surgically remove a player's love for the game, especially with so much excitement swirling around ASU's debut season in the Pac-12. In a wonderful gesture, Dennis Erickson afforded Threet an informal position as a student assistant, and he will serve as intermediary between Osweiler and the coaches.

"Brock is very receptive to all of this, and that says a lot about him," Threet said. "Because it's not easy to play behind somebody for a year, and then the next year, hear them try to tell you what to do.

"But Brock and I are good friends. I can sit down and get some points across to him, maybe things he'd have a harder time hearing from coaches, or maybe explain something in a different way. He understands we're both fixed on the same common goal, and that's winning."

The transition hasn't been easy. But Threet takes great solace that he will play a hand in the upcoming season. He plans on watching film with the coaches, and might even get around to eyeing the hit that sent him to the sidelines forever. By then, hopefully the headaches will have vanished.

Reach Bickley at dan.bickley@arizonarepublic.com or 602-444-8253. Read his online column at bickley.azcentral.com. Follow him at Twitter.com/danbickley. Listen to "Bickley and MJ" 2-6 p.m. weekdays on KGME-AM (910).