FLOWERY BRANCH, Ga. (AP) -- Atlanta Falcons coach Mike Smith has put a strong emphasis since the start of training camp on improving the team's run defense.
Smith sees incremental improvement, but stops well short of saying the Falcons have cured the ills that made them the NFL's second-worst unit against the run last season.
For Atlanta to succeed, Smith and his staff are putting major responsibility on second-year inside linebackers Paul Worrilow and Joplo Bartu, a pair of undrafted college free agents last year who emerged as starters and finished as the leading and third-leading tacklers.
''This is a huge opportunity for me,'' Worrilow said Wednesday. ''I don't approach it lightly at all. This is very important to me.''
Worrilow, a former Delaware standout, finished with 92 solo stops and played in every game with 12 starts. Bartu, a former standout at Texas State, started 13 of his 16 games, finishing with 53 solo tackles and tying for the team lead with seven tackles for minus yardage.
It was a whirlwind season for the two, but their on-the-job training was necessary when star linebacker Sean Weatherspoon was injured and Akeem Dent and Stephen Nicholas fell out of favor with coaches.
''I was just coming in here last year to produce and try to do the best I could,'' Bartu said. ''One thing led to another, and I was out there playing. I was fortunate to be able to get that playing time under my belt.''
Injuries to Sean Weatherspoon over the last two years forced both players to acclimate quickly to the NFL. The Falcons went 4-12 as their defense finished last in third-down efficiency and their offensive line all but collapsed.
Smith and defensive coordinator Mike Nolan have changed the base scheme to a 3-4 front. Bulk was added on the line in free agency with the signings of Tyson Jackson and Paul Soliai and in the draft with the second-round selection of Ra'Shede Hageman.
Defensive ends Osi Umenyiora, Kroy Biermann, Jonathan Massaquoi and Stansly Maponga have transitioned into outside linebacker spots.
''I think we've played the run much better in these two preseason games,'' Smith said. ''We had an explosive run (last week at Houston) that we had four or five missed tackles on one play, but having some girth up in front of them - some bigger players, guys that can stack blocks - our linebackers are going to have opportunities to make plays.''
Rookie Prince Shembo, a fourth-round draft pick from Notre Dame, has been taking snaps with the first-team defense to improve the depth at inside linebacker.
Shembo is playing both inside spots. Veterans Tim Dobbins and Pat Angerer and rookie Yawin Smallwood, a seventh-round pick, are also in the mix. The Falcons lost rookie Marcus Spruill, a fifth-round pick, to a season-ending knee injury two weeks ago.
Notes: Smith believes that RB Steven Jackson, sidelined since July 29 with a right hamstring injury, will be ready for the Sept. 7 opener against New Orleans. ''We're encouraged with what he's done on the side with the athletic performance group,'' Smith said while adding that Jackson's workload has increased even though he's not yet been cleared to practice. ... WR Julio Jones, who made his preseason debut against the Texans, said he feels no soreness in his surgically repaired right foot. ''No pain,'' Jones said. ''I'm still doing a lot of treatment, still doing my routine of one-day-on, one-day-off. Right now, they're going to increase the workload.'' ... Smith said that S Zeke Motta has been played on the active-physically unable to perform list and will miss at least the first six weeks of the season. Motta underwent neck surgery last December on his broken first cervical vertebra.
AP NFL websites: www.pro32.ap.org and www.twitter.com/AP-NFL
Follow George Henry at www.twitter.com/georgehenryAP