Even though her son tried to hide it, Carolyn Jackson sensed over the phone her son’s disappointment. And sometimes, David Sims was a little more direct.

“He was saying, ‘Mom, things aren’t working out like I thought they would,” Jackson said. “I’m thinking about transferring.”

In Sims’ freshman season, Jackson and Sims’ high school coach helped convince him to ride it out. Since then, the path has not been laced with daisies, but it has led to an unlikely point on the journey. A sophomore who came to Tech as a quarterback, Sims has earned the starting job in the featured B-back position in the Yellow Jackets’ offense.

On Thursday night, as dusk settles over Bobby Dodd Stadium, Sims will jog out with the first string to begin Tech’s season-opening series against Western Carolina.

“It’s just something I’ve been working for basically since little league,” Sims said. “To finally start in college football, I think Thursday night’s going to be something special.”

Sims himself conceded he didn’t expect to be in this position four weeks ago when Tech began preseason practice. After meeting with coach Paul Johnson at the end of the 2010 season and deciding that moving from quarterback to B-back would be his quickest route to the field, Sims became a B-back in spring practice. He entered spring fourth on the depth chart, did not distinguish himself in the spring and went into the summer still fourth.

He met again with Johnson, who told him that everyone on the team needs to find his role.

“I didn’t want my role to be fourth-string running back who switched positions,” Sims said.

Sims committed himself to working hard over the summer and learning the position. He ran extra sprints, worked with quarterback Tevin Washington and studied game video and his playbook.

“Whenever he came home, he brought his [football] homework home with him,” Jackson said.

When August arrived, Sims’ improvement was evident even before Tech began practicing in pads. He played his position more comfortably and quickly. His powerful leg drive and determined running found a home at B-back. He practiced at a feverish rate.

On plays when he didn’t get the ball “and they’re running down the field, and maybe he made a block, he’s getting up off the ground and he sprints another 20 yards,” quarterback and B-backs coach Brian Bohannon said. “There was a play out there he knocked two guys down in one play.”

Over the course of three weeks, Sims moved from fourth string to first at the deepest and probably most competitive position on the roster, passing Richard Watson, Charles Perkins and Preston Lyons. Bohannon called it “a pretty big jump,” which Sims wouldn’t dispute.

Given the competition, he said, “I was thinking if I could just stay in the conversation, then maybe I could contribute to special teams or something.”

That was not Sims’ thinking two years ago, when he redshirted after arriving from St. Matthews, S.C. In 2009, Joshua Nesbitt, Washington and Jordan Luallen were on the depth chart ahead of him. Synjyn Days was arriving the following summer.

Sims considered leaving Tech, not an unusual thought for a player who redshirts after hoping to play as a freshman. Sims said he never got to the point of considering his options, but said “it had gotten to where I was probably close to” leaving.

He chose to stay. In the summer of 2010, he was named the most improved player in the weight room. Last fall, he got into five games as a backup to Nesbitt and Washington. Then came the position change and what Sims called “a long, long process.”

It is only beginning. Perkins and Lyons are hot on Sims’ trail for playing time. But the former quarterback who almost transferred has earned first crack.

“It’s easy to bail,” Bohannon said. “Sometimes the hard thing to do is fight it, and he’s fought it. Hopefully, it’s going to pay off for him.”