They aren’t big. But Edwin Jackson and Kyle Oehlbeck know it, embrace it and will try to use it to their advantage because they may hold the keys to Georgia Southern’s season.

Jackson is projected to start in the middle of the team’s 4-3 defense. Though Oehlbeck is listed as a weakside linebacker, Georgia Southern coach Jeff Monken said he also will play inside.

Why is defense the key and not the Eagles’ high-powered triple-option offense? Though the offense returns three key playmakers, the defense lost four of its key playmakers. Jackson and Oehlbeck are being counted on not only to provide leadership, which can’t be quantified, but to make tackles and plays, which can be quantified … even if, at a combined stated weight of 436 pounds, they will be smaller than the players they are trying to tackle.

“I feel like it’s how you see yourself,” said Jackson, who is listed at 5-foot-11 and 222 pounds, but said he weighs 225. “I’ve been told I’m not fastest or biggest. It’s how you see yourself and your heart. How bad do you want it? I feel like me and Oehlbeck, being on the smaller side, we understand that if we aren’t good in this aspect, we have to be good in other aspects like being fast, and having nasty tenacity, holding onto the guy and being ferocious. If you want to make that tackle, you are going to.”

The defense lost five starters from last season’s team, which went 10-4 and made it to the FCS semifinals, losing to North Dakota State, the top seed and eventual national champ, 23-20. Oehlbeck was the team’s fourth-leading tackler (51) behind linebacker John Stevenson (103) , safety J.J. Wilcox (88), and safety Darious Eubanks (77), each of whom used up their eligibility.

Those who doubt that Oehlbeck, listed at 201 pounds but who said he weighs 211, has the size to hold up should keep in mind that Stevenson was listed at 202 pounds.

“It’s a mentality that we play with,” Oehlbeck said. “We will fly around. In spring time, we do make most of the tackles. No pressure to make it, but it’s a personal goal to get those tackles.”

Monken said he’s not concerned that the duo may not be considered big enough, pointing out that the Eagles have never had big players.

“In ’99, we went out to play Oregon State,” he said. “Friday, we bused to Corvallis for a workout. Oregon State equipment managers were waiting for us. One of them asked one of the coaches where the linemen were. Why didn’t the linemen come to the workout? We aren’t big, never have been.”

Like that history, Jackson has another tie that Monken appreciates.

Jackson enrolled at Georgia Southern as a student and tried out for the team in Monken’s first year. That’s the same path previously taken by Stevenson.

“When you come through the ranks you have something to prove,” Monken said. “You’ve got something about you if you can make it all the way from a tryout to a guy who is starting.”

Oehlbeck likes Jackson’s mentality.

“He’s bigger than me,” he said. “If it’s one thing I lacked it’s the size to pound those fullbacks in the hole. He’s just as fast as me. I love that he’s crazy; he’s a nut. I know if I can get one hand on the ball carrier, I know Edwin’s coming to wreck him. He’s like a security blanket.”

Jackson likes Oehlbeck’s wisdom.

“He says go, just go,” Jackson said. “If you are going to shoot the gap, go in and destroy.”

Both have worked hard in the offseason to get ready for the Eagles’ last season in the Southern Conference. Georgia Southern is joining the Sun Belt (and moving to FBS) in 2014.

Jackson spoke to former high school teammates at Westlake who are now in the NFL about what to look for when breaking down film. He said he used to be more of a “watcher” than an “analyzer.”

“I’m really excited, more than anything,” he said. “I feel like if you work for it, you can deserve it. I’m focusing on my craft and doing everything to the fullest.”