Once an unknown, Buffalo linebacker Khalil Mack is now a coveted 2014 NFL draft prospect. (Andrew Hancock/SI)

During spring practice earlier this year, Buffalo defensive coordinator and linebackers coach Lou Tepper made a joke that really irritated Khalil Mack. The Bulls were set to play Ohio State, a team coming off a perfect 12-0 campaign, to kick off the 2013 season on Aug. 31. The Buckeyes were tabbed as a preseason national title contender, and Tepper wanted to make sure his star linebacker was supremely motivated.

Tepper told Mack that people were calling him “just another guy.” Mack, 22, did what many sons do to blow off steam: He called his dad.

“[Khalil] said coach Tepper was kidding him about how the people in Ohio said he was just another guy,” Sandy Mack Sr. said. “They were calling him JAG. When he said it, I was like, ‘Uh-oh, man, I’ve got to get to that game.’ The sound in his voice. ... He really didn’t take that lightly. I knew something was going to happen that game.”

Against the Buckeyes, Khalil was anything but ordinary. He registered nine tackles and 2.5 sacks and had a 45-yard second-quarter pick-six. After he dove into the end zone for a touchdown, Mack sprinted toward the Buffalo cheering section, where his father and high school coach sat in attendance.

On the Monday after the Buckeyes’ 40-20 win, Ohio State coach Urban Meyer said Mack could “play anywhere at any school in America.” Now a senior, Mack's punishing play has NFL scouts abuzz.

Entering the year, the 6-foot-3, 248-pounder was pegged as a possible second-round pick in the 2014 NFL draft. Beginning with the Ohio State game, however, he’s played his way into top-10 consideration, according to ESPN draft analyst Mel Kiper Jr. Mack has a team-high 74 tackles, 13.5 tackles for loss, 7.5 sacks and three interceptions. He’s simply terrorized opposing offenses.

Yet to understand what makes Mack tick, one has to go back to another time, when someone called him a name.

BURKE: Khalil Mack sits at No. 9 in most recent 2014 NFL draft Big Board

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Family members joke around, and brothers and cousins tease each other. This has been the way of the world for as long as anyone can remember. When Mack was about 11, his cousin, Johnny Gamble Sr., a youth football coach, called him “soft.” Mack carries the insult with him to this day.

“I don’t know why he called me soft that time,” Mack said, “but I took it to heart. I don’t like that word.”

Growing up in Fort Pierce, Fla., Mack would compete with his brothers Sandy Jr., now 26, and LeDarius, 17, at everything. It was a mentality Sandy Sr. instilled in his sons stemming from his competitiveness with his own twin brother, Sammie Jr. During Khalil's upbringing, Sandy Sr. and Sammie Jr. would frequently play basketball in the driveway. Khalil would want to take part. He’d climb up the adults’ backs and try to hit them on the head in order to steal the ball.

Sandy Sr. said he didn’t get the chance to play sports as often as he would’ve liked as a kid, because his father, Sammie Sr., died in 1977 when he was 12 years old. Sandy Sr. and Sammie Jr. moved to Fort Pierce from Tampa in ‘78, and they mowed lawns and worked part-time jobs to help out their mom.

In turn, Sandy wanted his sons to take advantage of every possible athletic opportunity. He encouraged them to play anything and everything: basketball, baseball, billiards, bowling and, of course, football.

Khalil’s first football memories come from the park near the Boys & Girls Club across the street from his house. He wanted to mimic his older brother, and he begged to get into a game. When he finally got the ball, Khalil ran as hard and fast as he could to avoid being tackled.

He quickly realized he liked hitting people more than getting hit, and he would practice in full pads with Sandy Jr. They would line up and ram into each other as hard as they could. Khalil, being four years younger and much smaller, would get rocked and knocked to the ground. Then he’d get up and say, “let’s go again.”

“That’s where I gained a little bit of my heart and my will to not back down,” Khalil said. “Ever since that day, I’ve been a beast. I went out to practice the next day and went up against a guy in a tackling drill. I hit him so hard, he couldn’t get up.”

In Pee Wee and Pop Warner leagues, Khalil’s goal every game was to hit someone hard enough to make them feel it. He couldn’t shake the time Gamble called him “soft.”

As a senior, Khalil Mack has 74 tackles, 13.5 tackles for loss, 7.5 sacks and three interceptions. (Mike Groll/AP)

“There was a play one young man broke out and was headed down the sideline,” Sandy Sr. recalled. “I saw my son coming from the other side of the field and he came across and met him. When he met him, he almost hit him so hard he rolled for almost 10 yards where the parents were standing. They had to call the paramedics to come and get the young man. That was like, ‘Whoa,’ and was kind of scary. [Khalil] really wanted to prove to everyone that he was just as tough [as his brother] and he’s always been that way.”

As Khalil got older, he became much more passionate about basketball and tried to play his way to a scholarship. However, a torn patella suffered during a pickup game before his sophomore season derailed that plan. In the hospital, Mack’s grandmother emphasized the importance of making sure he went to college. Because of his injury, Khalil became fascinated with the rehab process, even taking classes at a local university after school. Had football not emerged as a possibility, he would’ve attended Indian River State College to become a physical therapist.

Khalil also became a workout nut, asking his dad for a gym membership so the two could rehab together. His strength continued to improve, and by the time his senior year began, then Westwood (Fla.) High football coach Waides Ashmon had taken notice.

“Out walks Khalil,” Ashmon said. “And the first thing that goes through my mind is, ‘Jesus Christ.’ Here comes this kid walking out about 6-1, about 215 pounds. You can see with clothes on, he’s just chiseled. My first question to him was, ‘What do I need to do to get you on the football field?’ He said, ‘Coach, you’ve got to talk to my dad, I had a knee injury, and you’ve got to talk to my dad.’ I opened my cellphone and called his dad right there in the hallway.

“I said I’ve never made this call before in my life, but if you allow your son to play football for me, he’ll go to school free.”

Mack’s senior season at Westwood was a blur, but coaches immediately realized he was more than just another guy. He recorded 140 tackles and nine sacks as the Panthers went 10-2. Still, because there wasn’t a lot of film on Mack, college programs were hesitant to extend an offer. Late in the process, he was set to attend FCS Liberty before the assistant coach recruiting him, Robert Wimberly, left the Flames to join Turner Gill’s staff at Buffalo. He invited Mack to come with him -- Mack’s first FBS offer.

The decision between Liberty and Buffalo wasn’t easy, especially after Mack saw a thick blanket of snow on the ground during his official visit to the latter. But Mack opted to become a Bull, thereby proving Ashmon true to his word that Khalil would go to school free.

“I appreciate the University at Buffalo,” Ashmon said. “They didn’t make a liar out of me to his father.”

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Once at Buffalo, Mack made his presence felt early and often. After redshirting in 2009, he set a school freshman record by racking up 14.5 tackles for loss in '10. He was named an All-MAC honorable mention both his sophomore year and junior years, and he was named to the SI.com Midseason All-America second-team in October. He has also been invited to the Senior Bowl.

Entering the home stretch of this season, Mack has shattered program records for career tackles for loss (69.5), forced fumbles (13) and sacks (25.5), among other categories. (He’s just one forced fumble and 5.5 tackles for loss behind the all-time NCAA records, according to Buffalo.) He’s the anchor to a defense that has the 7-3 Bulls set to play in just their second bowl game in school history.

After falling to Ohio State and Baylor to open the 2013 campaign, Buffalo required five overtimes to beat Stony Brook 26-23. Then the Bulls rattled off seven straight wins before falling to Toledo 51-41 last Tuesday. For his part, Mack is on his way to earning MAC Defensive Player of the Year honors.

Mack is always around the ball. He describes his style as instinctive and aggressive, and he embraces facing double teams.

“If they want to double team me, I love it,” Mack said. “It gives somebody else a chance to step up and make a play. I’ve been saying that for a long time. At the same time I don’t care about me or my opportunities to make a play, I just care about winning.”

Outside of an incident before his junior season in which he got into a fight with teammate Fred Lee (he was suspended for the team’s 2012 opener at Georgia), Mack has been nothing short of “boring” off the field, as Sandy Sr. puts it. Ashmon considers him a “big old teddy bear,” and Khalil spends as much time he can with his nieces. He also sings and plays the guitar.

When Khalil came to Buffalo, he may have been considered just another guy. With the 2014 NFL draft fast approaching, he’s anything but.

“I told him, ‘I don’t think it’s a coincidence you’re playing somewhere where they have a MAC conference,” Sandy Sr. said. “They’re spelling MAC all wrong. Before you leave, make sure they put the K on the end of it. It seems like he’s been trying to do that.”

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