How can a 6-foot-4, 265-pound defensive end help a secondary?

Just ask the defensive backs who played behind North Carolina's Robert Quinn, whose rare blend of size, strength and speed earned him the nicknames "Atlas" and "Big Freak" from his teammates.

"Just playing behind him you understand what he does for a defensive back," North Carolina cornerback Duenta Williams said. "At (East Carolina) two years ago, he sacked a guy so fast that I thought it was false start on the offense or something. I thought they were about to start the play over again. Just situations like that, you didn't have to do too much covering."

The 49ers have long been searching for a speed-rushing force that could harass quarterbacks and, in turn, mask breakdowns in the secondary. The Niners haven't had a player post more than 8? sacks in a season since 2002 when Andre Carter had 12?. They have played primarily a 3-4 defense since 2005, but have yet to locate a pass-rushing outside linebacker that's vital to the scheme.

Last year, they used a four-man rotation at outside linebacker consisting of Parys Haralson, Manny Lawson, Travis LaBoy and Ahmad Brooks. The underwhelming quartet managed 16? sacks, one more than Cowboys outside linebacker DeMarcus Ware.

When asked about his outside linebackers earlier this offseason, new defensive coordinator Vic Fangio offered a lukewarm assessment that ended with this admission: "We're searching."

That search brings us back to Quinn, a projected top-10 draft pick who, at 265 pounds, ran the 40-yard dash in 4.57 seconds, had a vertical leap of 33 inches and posted a broad jump of 10 feet, 6 inches at his pro day. Big Freak, indeed.

During the NFL Combine, NFL Network draft analyst Mike Mayock said of Quinn, "He's as good a natural pass rusher as I have ever seen."

Texas A&M linebacker Von Miller, the draft's premier pass-rushing demon, will likely be off the board when the Niners pick at No. 7 and Quinn is widely regarded as the next best option.

The 49ers, however, would likely be envisioning Quinn as their long-awaited 3-4 outside linebacker. And it's believed that Quinn's ideal position in the NFL is defensive end.

"I do believe that he can be a good, or perhaps even very good, 3-4 rush linebacker," CBS Sports draft analyst Rob Rang said. "But I believe he could be a Pro Bowl defensive end. That's where I see him as an ideal fit in the NFL."

Of course, Ware and Kansas City's Tamba Hali are former college defensive ends with Quinn's dimensions that are starring as 3-4 outside linebackers in the NFL. Ware (6-4, 262 pounds) and Hali (6-3, 275) ranked first and second, respectively, in sacks in 2010.

Beyond his position at the next level, there are other questions surrounding Quinn, who hasn't played a game in 16 months since he was declared permanently ineligible by the NCAA for accepting $5,642 in benefits from agent. Quinn, who only played two years in college, reportedly lied to NCAA and UNC officials about the gifts.

Despite that misstep, there aren't character concerns surrounding Quinn, 20, who came across as humble and genuinely remorseful in his meeting with the media at the combine.

"I made a selfish mistake and I paid a price for it," Quinn said. "And my team and my family and coaches paid a price for it. I truly apologized for it."

Of perhaps more concern to NFL teams is the fact that Quinn has a benign brain tumor, which was diagnosed when he was a senior at Fort Dorchester (S.C.) High School. He had surgery to reduce the fluid backup and was told he would never play sports again.

A few months later, however, he won his third straight state heavyweight wrestling title. As a freshman at UNC, he won the Brian Piccolo Award given to the ACC's most courageous player. Then, as a sophomore, he led the conference in tackles for loss (19) and ranked second in sacks (11).

Quinn, who says he hasn't a tumor-related headache since his surgery, still undergoes an MRI exam every six months to monitor the tumor.

Given his background, it's not surprising that a potential position switch in the NFL doesn't phase him.

Could he be an effective linebacker?

"Whatever I set my mind to," Quinn said. "If they want me at free safety, I'm going to go play it for you. I really think I can."