ATHENS — RPO. It is an acronym that is sweeping through college football, and it’s a dirty word for defenses.

It stands for “run-pass option,” and Georgia has seen it to varying degrees in all four of its games this season. The Bulldogs saw it a lot last week at Ole Miss, which obviously did not go well, and they might see it even more this Saturday when No. 11 Tennessee comes to Sanford Stadium.

Essentially, the concept that is any play can be a run or pass, depending on what the quarterback reads. College football rules have allowed this to be very effective strategy because it allows offensive linemen to fire off the ball on a pass play as long as they don’t venture more than three yards up the field. Pro football, in contrast, does not allow linemen to advance down the field at all on a pass play.

“It’s extremely difficult because, whatever you grew up doing fundamentally — which is, you key for the run or pass, you diagnose, you make a decision, and then you go play the play — now those two are combined,” said Georgia head coach Kirby Smart, a defensive coordinator at Alabama the last eight years. “So you’ve had to change the way you coach fundamentally.  Guys that don’t have responsibility on the run, they can’t be involved at all.  They’ve got to take care of their job.  And there’s another group of guys that have to take care of their job.  It makes you play defense a certain way, when you have the RPO systems.”

For those grousing about the Bulldogs’ lack of sacks this season, facing a bunch of RPO teams is the chief reason for that. Georgia has only four quarterback sacks all season and is 13th in the 14-team SEC in that statistical category as a result.

Florida leads the SEC in that department with 17, or 4.25. But even the Gators struggled in that regard this past Saturday facing Tennessee quarterback Josh Dobbs and the Vols’ RPO system. They logged one sack for eight yards. Meanwhile, Dobbs completed 16-of-32 passes for 319 yards and four touchdowns. He also ran the ball 17 times for 80 yards and another score as Tennessee scored 38 unanswered points in a 38-28 victory.

Dobbs, a 6-foot-3, 220-pound senior from Alpharetta, had a similar performance in the Vols’ come-from-behind win over Georgia last year in Knoxville. He finished with 312 yards and three touchdowns passing and ran for 118 yards and two more TDs.

Defending the RPO concept is difficult as it is. Add a mobile veteran quarterback such as Dobbs or Chad Kelly of Ole Miss, and it can be almost impossible to defend. It’s especially challenging for outside linebackers and defensive ends, who are charged both with providing containment and generating pressure on the passer.

“It’s very frustrating,” said Georgia junior outside linebacker Davin Bellamy, who leads the Bulldogs with seven QB pressures and had one half-sack. “It kind of takes away your tenacity. You’ve kind of got to play your keys and not just get off the ball and go do what you want to do. You’ve got to make sure you’re in the right position for everybody.”

Georgia did a decent job of defending North Carolina’s RPO package in the season opener. They limited the Tar Heels to 315 yards overall and only 17 offensive points. Nicholls State ran it to a lesser degree with less sophistication the next week and managed only 236 yards.

But Missouri and Ole Miss both bank on the strategy almost exclusively and had their way with the Bulldogs for long stretches. The Tigers’ Drew Lock had 376 yards passing and three touchdowns but his good work was undone by three interceptions. Georgia had no answer at all for the Rebels’ Kelly, who had 282 yards passing and two touchdowns and added 53 yards rushing, including a 41-yard touchdown run.

Georgia had some opportunities but didn’t cash in. On one play, outside linebacker Lorenzo Carter should have had Kelly for a sack. But he tried to tackle Kelly high and Kelly shook off Carter. He then stepped up and delivered a touchdown pass put the Rebels ahead 24-0 in the second quarter.

“‘Zo’ should be second in the SEC in sacks right now with three. So, yeah, sacks will come,” Bellamy said. “But I think we do a pretty good job of affecting the quarterback. I kind of think people get confused. Sacks aren’t everything. You still have to play football, and we’re doing a great job of playing our keys and striking people up front and spilling stuff to the linebackers. That’s stuff that doesn’t show up on the stat sheet.”

Dobbs represents the biggest challenge the Bulldogs will have faced from a running standpoint. He’s the Vols’ second-leading rusher with 241 yards and has four TD runs. But he’s also surrounded by more weapons than any team Georgia has faced. Running back Jalen Hurd (6-4, 240) is a big and bruising runner, Alvin Kamara is a speed demon and UT features one of the tallest receiving corps the Bulldogs will face, from 6-6 tight end Ethan Wolf to 6-3 wideouts Josh Malone and Jauan Jennings.

“Some people are more elaborate at it than others,” Smart said. “It takes a good quarterback to do it, too, because you’re not protected, and he’s got to get rid of the ball really quick.”

As for the trend of designing and developing an offense built around the RPO concept, Tennessee stands as Exhibit One of how and why you do it.

“It has changed the game a lot, especially at my position,” Bellamy said. “At outside linebacker, D-end, you can kind of play off instinct when you play teams with normal-style offenses. But these spread and RPOs take some of the instincts away because you’ve got to play your keys and make sure that you’re fitting up right. If you don’t then there will be gaps in the defense.”

If there is a chink in the armor of this offense it’s turnovers. Since quarterbacks are having to make such quick decisions with the football, they can make some bad ones. Kelly committed devastating turnovers in losses to Florida State and Alabama. Dobbs comes into Saturday’s game with five interceptions and the Vols have fumbled the ball 12 times. Remarkably, they’ve recovered all but one of those loose balls.

And while Georgia’s secondary looks overmatched from a size and athleticism standpoint, the Bulldogs do have a propensity for getting their hands on footballs. They’ve logged nine takeaways this season – second only to Missouri’s 10 in the SEC – including six interceptions, and come into the contest with a plus-2 turnover margin. Juwuan Bruiscoe and Quincy Mauger are tied for the SEC lead in interceptions with two each, and free safety Dominick Sanders led the SEC last year six picks.

“That interception we had last week was Ole Miss’ other quarterback,” Smart said. “It was an RPO and he didn’t get it out of his hand quickly enough. The other guy (Kelly) was getting it out quick, and Josh Dobbs gets it off quick.  He does a good job with a quick release.”

The key for the Bulldogs on Saturday is winning first and second down and forcing the Vols into predictable passing situations on the third down. That way their options are limited Georgia can have a better idea of what’s coming at them.

“One thing we didn’t do last week is we didn’t get them into tough third-down situations,” Bellamy said. “They had a lot of third-and-two, third-and-three, third-and-four. So in practice we’re focusing on being more physical and getting them in those third-and-long situations so we can get them off the field.”

Easier said than done.