Less than two years ago, Cole Gardner was a tight end at Eastern Michigan when his head coach asked him to be something bigger than himself.

Gardner, now an undrafted rookie with the Bucs, had spent three years as a tight end, catching 10 passes and a touchdown, but had struggled to stay within a 6-foot-5, 250-pound frame.

"'You're a good tight end, but we think you can be a special tackle," coach Chris Creighton told him. "You're essentially starving yourself on weigh-in days to try to keep a tight end weight. Think about that.' He came back and said 'I'm all in.'"

Gardner put on weight in a hurry, working with the school's training staff and taking in 6,000 calories a day with the help of protein shakes, and he played that season as a 285-pound tackle, returning at 300 pounds his senior year. He served as left tackle on an EMU line that gave up 13 sacks -- second-lowest in the Mid-American Conference -- while attempting a league-high 509 passes.

"You're going from catching passes to never seeing the football," Creighton said. "He was 100 percent all in, mentally, physically, emotionally and never looked back."

Gardner, 23, said he had confidence as a tackle with the added weight because he was able to keep much of the athleticism he had as a tight end, and before that in basketball, earning conference Player of the Year honors as a junior in high school. The Bucs have had success in recent years with undrafted rookies, and this year's search for another diamond in the rough starts with Cole.

"I still feel athletic. That was the biggest thing for me," he said. "That gave me my edge when I made the switch. That was a big goal, trying to keep the athleticism while putting the weight on. This offseason definitely helped me as well."

By coincidence, Gardner trained this spring back in Illinois with Bucs tight end Cameron Brate -- his hometown of Batavia is about 15 miles from Brate in Naperville -- so he had a familiar face in the locker room from the start. He was the only lineman in his training group, which kept him surrounded with faster athletes.

Gardner is back in Tampa now after a week off following rookie minicamp -- his priority in the next two months is learning a complicated offense and playbook, hoping that by training camp in late July, he's comfortable with what the Bucs are running and how offensive line coach George Warhop likes his tackles to play.

"I'm working on the techniques that Coach likes," he said. "Every offensive line coach is different, so you adjust to the specific things they like."

The Bucs have solid experienced depth at guard and center inside, but less so at tackle -- behind starters Donovan Smith and Demar Dotson, the Bucs only have Leonard Wester, another developmental player who was an undrafted rookie last season. The Bucs didn't draft an offensive lineman, and have Alabama's Korren Kirven as the only other rookie lineman on roster.

"Going in, you always look at the team and give yourself the best option to go and impress the coach and make that 53-man roster. That's everyone's goal," he said.

Gardner pays close attention to the best tackles in the NFL -- one of his favorites is Browns tackle Joe Thomas, and if he can stick around through August, he'll get a chance to meet him when the Bucs play host to Cleveland in the third week of the preseason.

Back in college, Creighton had told him he'd do everything he could to work a pass play to his left tackle into the playbook, for old time's sake. Sure enough, last fall, in a rivalry game against Western Michigan, facing a fourth-and-1 at the WMU 24, Creighton called a pass to Gardner for a 5-yard gain, only to have it called back on a penalty.

"He caught it and ran with it but it didn't count," Creighton said. "That was me keeping that alive. He 100 percent dove in to being an offensive lineman. They've got a great player and even better person, everything you want in a football player. Does he have room to grow? Potential to get better? Absolutely. No question."