FOXBOROUGH — When he was young — as in first- or second-grade young — and just starting his football-playing days in Shelby, N.C., Brandon Spikes remembers the other parents’ complaints during his Pop Warner games.

“They would say, ‘He’s hitting too hard! He must be too old!,’ ” Spikes recalled, smiling at the memory.

But Spikes was just doing what his older brother taught him to do, and what now has become ingrained in him.

“When I was playing, he said, ‘If you want to play defense, you have to have killer instincts, that mentality — you have to be violent and do it throughout the entire game,’ ” said the Patriots linebacker, “and it just stuck with me.

“So that’s all I know. It’s just in me.”

After missing seven games in the second half of the 2011 season, Spikes returned to the field just in time for the postseason and was impressive in the three playoff games, totaling 27 tackles, recording his first career sack, and forcing a fumble in each.

He was showing in games what he had shown defensive leaders in the meeting rooms and on the practice field already: that he was starting to put it all together.

“I saw it last year, toward the end part of the year,” said Vince Wilfork. “Seeing how he carried himself, the work he put into it, he just seemed transformed. I remember me and [Jerod] Mayo were sitting and talking one day, and that’s one of the conversations — ‘You know what? Brandon is starting to become a top-notch player for us because he elevated his game.’ ”

A second-round pick out of Florida in 2010, Spikes has played in just 21 regular-season games to this point in his career. As a rookie, he missed the final four games to a league suspension for violating the performance-enhancing drug policy, then the first game last year to a groin injury before a knee injury cost him the seven games later.

When he returned, it was clear that he made a difference for the defense.

A healthy Spikes could be a vital part of the success of that unit this season. With Dane Fletcher injured and Bobby Carpenter released, there is not much depth behind Spikes, Mayo, and Dont’a Hightower at the linebacker position. Tracy White is a career special-teamer who did get spot duty last year (and started the Super Bowl), and Mike Rivera has yet to play in an NFL game.

But it isn’t just Spikes’s play that is appreciated by teammates; it is also the intangibles he brings.

When asked what a healthy Spikes can mean, Wilfork lets out a “pssh,” like air leaking from a tire.

“His presence on the field alone, the way he plays, he just brings that energy, that physicality that we want to play with, that intensity we want to play with, that’s what he brings to us,” the veteran lineman said, noting that Spikes also has tremendous passion for the game. “When he’s able to go, he goes.

“And you know, he worked his tail off this year to make sure he could come in [to training camp] in good shape and be able to play. But with him on the field, it’s different from when he’s not on the field, just a lot of stress on the defense because of depth and what he brings to the table.

“I’m looking for a big year from him and I’m pretty sure he feels the same way.”

Spikes acknowledges that he’s maturing as a professional football player, that he’s learning the tricks of the trade, so to speak, the importance of good nutrition, training consistently in the offseason, putting in the extra time in the classroom.

It frustrated him to miss so much time last year, time that he could have been “on the field with my teammates, having fun playing the game I love.” But he also readily admits that there may have been a silver lining in being relegated to the sideline.

“It kind of helped me a lot,” he said. “I had time to do the things that I needed to do in order to take the steps as a professional to get better. It helped me, but like I said, I missed significant time, so I didn’t like that. But other than that, it helped me out.”

He prefers middle linebacker in a 4-3 because that’s how he played in college and is the position he feels most comfortable playing.

However, the position Spikes loves may not love him back in the current NFL landscape.

He modeled his game after Hall of Famer Dick Butkus, and wore 51 at Florida as an homage to the Bears star, and were this 15 years ago or even five years ago — before nearly every team became a pass-first offense and tight ends became athletic freaks whose size belies their speed — Spikes might be bound for elite status.

But two talent evaluators — a current team scout, and a former front office executive — wonder if Spikes is fast enough to play a major role. He played almost exclusively on first and second down against the Titans a week ago, coming off the field in obvious passing situations.

The knock on Spikes when he entered the draft was his lack of speed, and that could be hurting him now. Both talent evaluators said Spikes might be better suited for a 3-4 alignment, where he can be more of a thumper or a Jack linebacker, a hybrid defensive lineman/linebacker.

New England started both the AFC Championship and the Super Bowl in 3-4.

“He looks the part, looks like he knows what he’s doing, looks like he has instincts,” the exec said. “He’s a key on run downs, running situations. [But] he’s not the person you want in there to cover anyone in [man-to-man]; when he’s in coverage, he’s in zone. His importance to the defense is in the running game.”

The problem with that is that not many teams field power-running offenses anymore. If they did, Spikes would be in his element, snuffing out running backs as they hit the line.

He put in the work last year and this offseason to take the next step in his development, and Spikes may need to put in a few more hours to carve out a niche for himself on the revamped defense.

He knows he has to play through the nicks and bruises that come with being such a hard hitter to get through a season healthy for the first time.

“I haven’t done it yet, so I’m going to strive for that.

“Pray for me,” he added with a laugh.

If he’s healthy, if he can be on the field not just game to game but for as many snaps as possible, it would be Spikes and his violent tackling style causing the bruises.

“You know what, the way he plays, you have to play like that. He’s a ’backer,” Wilfork said. “When you talk about the greatest ’backers in the game, you just go down the list and you start seeing how they tackle, how they approach the game, how they hit people, and he has everything in him.

“That’s how Spikes is; he wants to go out there, he wants to hit, and he loves the game.”

Shalise Manza Young can be reached at syoung@globe.com