(The second in an occasional series that looks at college players who could be selected by the Patriots in next month’s draft.)

Clay Matthews III has heard it all his life.

Most 5-foot-7, 120-pound high school freshmen aren’t entertaining thoughts of life in the NFL. They’re not even thinking about playing high school football. They’re more concerned with not getting stuffed into a locker. Football? Really? Maybe you want to give something else a try. I hear the chess team is having tryouts tomorrow.

But according to his father — former NFL star Clay Matthews, Jr. — he wasn’t your average football-playing freshman. Early on, the son developed a singular vision, and he wasn’t going to let something as insignificant as his size get in his way. He found a spot on the Agoura High team, eventually put some weight on — 45 pounds by his senior season — and became a starter at Agoura High, reaching all-league and all-county status.

“He didn’t play a lot until he was a senior,” said Matthews’ high school coach, Charlie Wegher. “He had it all to that point. He was a smart, tough, physical guy who worked hard. When the body finally arrived, he was ready.”

Ready for high school football, sure. But the Pac 10? By this time, Matthews was six feet and just under 200 pounds. The University of Southern California didn’t have a scholarship, even for a guy who had an uncle, father and grandfather who played in the NFL. There were options — junior colleges and 1-AA teams were interested — but Matthews wanted to walk-on at USC, following in his father's footsteps, who also played for the Trojans. USC? Really? You’ve had a nice career, Clay. Maybe you want to try something else when you get to college?

“It was his vision,” said the father. “When he said he was going to USC, we all said, ‘Are you sure?’ It was his vision. He deserves all the credit.”

“I thought it was intriguing,” USC coach Pete Carroll told reporters earlier this year. “He had that big family background here. So I thought, ‘OK, is there some magic in here somehow?’ And I didn’t see it. He looked like just a good, hardworking kid who was undersized, just not physically ready to match up.”

So Matthews walked on. He started as a special teamer, eventually working his way up the depth chart to become a starter three games into his senior season. Playing the “elephant” role in the USC defense last season — a hybrid linebacker/defensive end — Matthews posted 56 tackles and finished third on the team in tackles for loss (9.5) and second in sacks (4.5).

Along the way, he put on a few more inches and 40 more pounds. It’s funny the way doubters clam up when you’re 6-foot-3 and 240 pounds.

“He’s really grown into a completely different player,” said fellow USC linebacker Brian Cushing. “He came from a walk-on, a skinny guy, and he just worked his way up all five years. He’s done a great job. He’s learned more, he’s just adapted to the system, and overall he’s just improved his stock tremendously.”

Entering the draft, the tangibles are there. He killed at the combine, finishing in the Top 5 among all linebackers in 20-yard shuttle (4.18), the three-cone drill (6.9), the broad jump (10-feet-1), vertical jump (35 1/2 inches) and 40-yard dash (4.67). And the pedigree is peerless — he was raised in the culture of football. His uncle (Hall of Famer Bruce Matthews), father (Clay, who played 19 years in the NFL, including three seasons for Bill Belichick in the early 1990s in Cleveland) and grandfather (four seasons with the 49ers in the 1950s) all played the pro game.

But it’s the overachiever/special teams/versatility that has teams looking hard at Matthews as a first-rounder. He’s cool with that.

“Obviously, coming in as a walk-on, I knew I’d have to make my name through special teams,” Matthews said “And that does sit well with many NFL teams in the fact that they’re only allowed to dress so many players and a lot of them need to contribute on special teams. And that’s what I consider my bread and butter, and that’s what got me to where I am today and to be able to play linebacker. It’s just something I really appreciate and understand the value of and would love to do for years to come.”

“The people who think he’s just a ‘try-hard, overachiever’ are wrong,” said NFL Network analyst Mike Mayock. “He was a former walk-on. He’s gained 55 pounds of muscle since he got there. He’s got athletic skills. And of all the USC linebackers, he can rush the quarterback better than any of them. I think he’s a solid, second-round kind of guy that’s going to start for somebody early in his career and play 10 years.”

“I think that’s part of the beauty of him, his versatility. I think he’s probably a 4-3 ‘will.’ But I know teams are looking at him for different things. And I think in today’s NFL, the more you can do from a versatility perspective, the better off you are.”

Setting aside the relationship between the elder Matthews and Belichick — who has said he was “lucky” to get a chance to coach someone like Matthews — both his father and Wegher believe the 22-year-old would be a classic fit in New England, which holds the 23rd and 34th overall pick in next month’s draft.

“Absolutely. He’s a total team guy. He’s about doing what you tell him to do. He will be a team player in the pros, just like he was in college and in high school,” Wegher said. “I know that’s what they base that organization on — Clay is that kind of guy. He just enjoys the game. I think he’d be a perfect for them.”

“I was always impressed with the way that Bill took a real thorough approach to the team. Everything was analyzed,” Matthews’ father said. “For a player, you were always put in position where you had the best chance to succeed. And speaking selfishly as a father, you always want to see your son put in a position where he will be successful. And you know Bill does that.”

And those doubters that dogged Matthews as a high schooler and collegian? They seem to have disappeared. The NFL? Really? Think you can try and get me some tickets?

“It’s been a career of ups and downs, and obviously walking on is not a typical path of someone going to SC and being in the position I am today,” Matthews said. “But it took a lot of hard work and dedication and there were some ups and downs and who knew I would be in the position I’m in today, but here I am and I’m fortunate.”

Christopher Price covers the Patriots for WEEI.com.