ATLANTA — The question arose even before Paul Johnson was introduced as Georgia Tech coach in December: Would he continue to use the triple-option offense that worked so well for him at Navy?

The answer was yes, which led to more questions.

What's an A-back? What's a B-back? What's a spread option, Johnson's preferred moniker for the offense?

But the one question that really irritated Johnson: Could the scheme that thrived at Georgia Southern and Navy have success in a BCS conference such as the Atlantic Coast Conference?

"That's the thing that's hilarious, 'At this level,' " Johnson, a former University of Hawai'i offensive coordinator, said before the season. "I mean, what? Are we in the NFC East?"

After six games, most of the remaining questions about Johnson's offense are from opposing defensive coordinators. Such as, "How do we stop this thing?"

Georgia Tech, which plays at Clemson on Saturday, is 5-1 overall and 2-1 in the ACC, including a win at Boston College in Johnson's conference debut.

Georgia Tech is eighth in the nation in rushing at 255 yards per game even after its only poor performance, 79 yards rushing in last week's ugly 10-7 win against Gardner-Webb.

"Certainly you can tell he feels vindicated a little bit," offensive tackle Andrew Gardner said Tuesday. "He had to answer a million questions about can he be successful and certainly we've shown in some games we can be and we've beaten some good teams. You can see he's pleased when it works and it comes together."

The Gardner-Webb game can be dismissed as an aberration. The Yellow Jackets may have been looking ahead to Clemson. More important, they were without their top two quarterbacks, Josh Nesbitt and Jaybo Shaw, and the offense fell flat.

"When you're beat up and you're playing with some backup guys and you come out that way, you're going to struggle," Johnson said. "I don't care who you play."

Nesbitt and Shaw are both back this week. Nesbitt, who strained a hamstring on the first possession of the Yellow Jackets' 38-7 win against Mississippi State on Sept. 20, is expected to start. Shaw, a freshman who led Georgia Tech to 438 yards rushing and 500 total yards against Mississippi State, should be ready, too.

For all Georgia Tech's success, the Yellow Jackets don't believe the offense has peaked.

"As we get more comfortable with the system, I think you'll see our ability to put in more stuff and make more adjustments," Gardner said. "I think we're getting to that point where we know the offense much better than we did."

There's nothing plodding about Georgia Tech's ground game. The Yellow Jackets have 36 plays for 20 or more yards and 13 touchdown drives have lasted 3 minutes or less. The Jackets don't throw it much, but they do it often next them big yards. They've averaged 20.8 yards on 35 completions.

Jonathan Dwyer, who leads the rushing attack from the fullback-like B-back spot, rushed for 141 yards and a touchdown on only nine carries against Mississippi State.

Bulldogs coach Sylvester Croom, who played for Bear Bryant in a wishbone offense at Alabama, knows option football but his defense couldn't stop Johnson's scheme.

Croom said the difficult twist to Johnson's attack is the way the two A-backs line up wide instead of behind the quarterback and Dwyer. The A-backs spend most of their time blocking and running the ball, but they're also threats as receivers.

It's an option attack that doubles as a four-receiver set.

"It adds some more elements to it in the passing game that creates more problems," Croom said. "Whereas when we were in the true wishbone with the backs in the backfield, there were no full verticals in a pure-wishbone. But this offense with those guys placed up there in almost tight end positions, they can still attack you with four vertical receivers. That creates some problems because you have to have eight guys down there to stop the option."

Duke coach David Cutcliffe had the advantage of facing Navy, which still runs Johnson's option, before preparing for his Oct. 4 game at Georgia Tech. The Blue Devils still gave up 17 fourth-quarter points in a 27-0 loss to the Yellow Jackets.

"Paul Johnson, I don't think there's anybody that knows the offense as well as he does, no offense to the people at Navy," Cutcliffe said. "He knows the offense, he knows how to adjust it, he knows if you do this, then he's going to do this."

Johnson insisted from the start that Georgia Tech could pass out of the spread option, and Shaw proved it with 230 yards passing against Duke, foiling the Blue Devils' focus on the option. All of Shaw's yards passing, including an 88-yard touchdown pass, were to Demaryius Thomas.

Johnson still frets about the close loss at Virginia Tech, injuries and his team's lack of depth, especially at running back and on the offensive line.

"I think we're making progress, but it would have been far better if we'd have had some consistency and stayed away from injuries," he said.

Asked what he would have said if told before the season his team would be 5-1, Johnson shook his head.

"I would have tried to be 6-0," he said. "I wouldn't have taken it."