When he reviewed the play of his defensive line during the 2010 season, Washington Redskins defensive coordinator Jim Haslett came to the conclusion that the unit wasn’t as effective as it should have been. A big reason for that, Haslett realized, was the linemen wore down as they reached the homestretch.

Aside from Adam Carriker, who had three of his better games in the final five weeks of the season, the line as a whole fizzled in the final month of the season, and three players — Kedric Golston, Ma’ake Kemoeatu and Phillip Daniels — wound up on injured reserve in December.

The Redskins acquired four more defensive linemen in the offseason, drafting end Jarvis Jenkins and nose tackle Chris Neild, and signed free agent nose tackle Barry Cofield and end Stephen Bowen. (Jenkins won’t get to play his rookie season after tearing an ACL in the preseason.)

Haslett this season has focused on maintaining a more frequent rotation to keep his defensive linemen fresher. Carriker, Cofield and Bowen start, but Golston and Neild shuttle in and out frequently, and Haslett is seeing the payoff.

“I think all of those guys are playing less snaps because we’re using five guys,” Haslett says. “Even [Neild] played a lot last week, 12 or 13 snaps, which is more than he [normally] plays and we gave [Cofield] less snaps, so I think that helped those guys. As the season goes on, last year, with our age and all of the snaps we were taking, we were on the field way too much [and] we just kind of fell apart at the end of the year. I don’t foresee that this year.”

Carriker and Golston have improved significantly over last season — partially because they are more comfortable in the system and partially because they are fresher. Carriker, who had just 1.5 sacks last season, already has 4.5 (tied for the team high) this season. Golston is on pace to equal last season’s tackle total of 35 and after going sackless last year, he is projected to finish with 3.4 this year despite playing fewer snaps. Carriker and Golston also have been the most effective against the run when playing in the nickel packages together.

Bowen, who leads the linemen with 19 tackles and also has 3.5 sacks, and Cofield (11 tackles, 2.0 sacks) have had some ups and downs as they acclimate themselves to Haslett’s 3-4 scheme, as has Neild.

The Redskins are working to shore up their run defense, but Haslett says he’s encouraged by what he has seen so far.

“I think they’ve done a good job,” says Haslett, whose line has 13 sacks this season after getting just four all of last season. “Obviously, the numbers are much better than they were last year at this time and I think our players are better. If you just go from that standpoint, at this midpoint, I think we’re a much better football team.”