Four games are in the books, and the Washington Redskins have reached their bye week. The jury still is out on this team as three-quarters of the season remains. But we’ll take this time to evaluate the team at its current state. Today features a look at the defense, Wednesday we examined the offense and on Friday special teams.

A year after fielding the league’s 31st-ranked defense, the Redskins needed to make a big leap in Year 2 under coordinator Jim Haslett. And thus far, they have. At the season’s quarter-pole, Washington is allowing just 296.5 yards per game, fifth-best in the NFL.

After the team upgraded its personnel in the offseason, adding pieces better-suited for the 3-4 scheme, the Redskins have shown improvements across the board. They’re stopping the run (84.5 yards per game, sixth-fewest in the league), putting pressure on the quarterback (with 15 sacks, they’re tied with Philadelphia for first in the NFL) and getting off the field on third downs (opponents have converted just 13 third-down attempts thus far). In fact, Washington is tied with the New York Jets for the best third-down percentage in the league (26 percent).

Through four games, the Redskins have allowed just six touchdowns. Only the Ravens and Titans have allowed fewer. And only the Jets have allowed fewer than the three passing touchdowns given up by Washington.

Haslett has talked a lot about an aggressive defense and his team’s play reflected it in the first quarter of the 2011 season. The Redskins have shown a variety of blitz schemes, have attacked quarterbacks and thus far have notched seven forced fumbles, tied for second in the NFL.

While many might look to the addition of rookie Ryan Kerrigan as the biggest upgrade, the overhaul of the defensive line has made a huge impact. They’ve not only opened lanes for linebackers and found success stopping the run, but the line has also steadily made plays of their own. A year ago, the Redskins line accounted for nine sacks the entire season and didn’t force a single fumble. Through four games this year, Washington linemen have 6.5 sacks and one forced fumble.

Bright spots:

> Outside linebackers — The early successes of Kerrigan and Brian Orakpo should give Redskins fans reasons to smile for years to come. The pair is on pace to tally 24 sacks this season.

Despite missing out on offseason instruction due to the lockout, Kerrigan has quickly adapted to the linebacker spot in the 3-4. He made his presence known with an interception return for a touchdown in the season-opener. He also has notched 2.5 sacks and forced two fumbles; no one in the NFL has forced more.

Rushing the edge from the opposite side, Orakpo is tied for 12th in the league with 3.5 sacks. The addition of Kerrigan means teams can no longer focus their efforts on Orakpo. Thus far, they’re both benefiting.

> New acquisitions — The Redskins added five new starters on defense and the results suggest they were pretty wise additions. Up front, Barry Cofield has shown no problems adjusting to the nose tackle position, and Stephen Bowen, in his first season as a full-time starter, has also represented a significant upgrade. Free safety Oshiomogho Atogwe is third among starters with 13 unassisted tackles.

Cornerback Josh Wilson has shown good coverage skills, but he’s still searching for his interception and can afford to improve tackling. He leads the team with four defended passes, which ties him for 16th in the league.

> Familiarity with 3-4 — The returning players are all improved in their second year in Haslett’s system. They’re moving more instinctually and look more natural executing the coach’s playcalls. Insider linebacker Rocky McIntosh leads the team with 27 tackles and seems to be around the ball more than a season ago. Adam Carriker is more of a force, too, and his 2.5 sacks are 2.5 more than he had a year ago.

Areas of concern:

> Defensive line depth — This hasn’t been a big issue through four games, as the Redskins have comfortably rotated in Kedric Golston and rookie Chris Neild. But if just one lineman goes down, this could quickly become a problem area. Neild, who had 1.5 sacks in the season-opener, has seen increasing amounts of action and is committing fewer mental mistakes.

> Safeties tandem — LaRon Landry missed the first two games because of a sore hamstring, and Atogwe has been slowed by a hamstring injury he suffered in training camp. Coaches hope both return healthier after the bye week and can be as dominant in the defensive backfield as they’d hoped in the offseason.

> Interceptions — Ideally, the pressure on the quarterback will result in more interceptions. The Redskins have only three through four games — none from their two starting cornerbacks and none from any safeties.

What we know so far:

The Redskins’ defense has kept the team in games, and there’s no way Washington would be 3-1 if the team’s defense hadn’t performed so well.

Criticized at times for being too aggressive — the zero-blitz on third-and-21 at Dallas comes to mind — the Redskins feel comfortable with their personnel to take risks. Coaches figure the rewards are worth it. And more often than not, they have been.

Redskins fans for years enjoyed a top-10 caliber defense. But that was usually a unit that limited opponents’ yards. Haslett’s unit might give up some yards, but it’s intent on causing turnovers, scoring touchdowns and making big plays.

They’ve been doing that thus far -- and doing it while a couple key playmakers have been relatively quiet. A healthy Landry and Atogwe should make for a more dynamic secondary and give Haslett more blitz options in the final 12 games. Pro Bowl cornerback DeAngelo Hall is still looking for his first interception, as well.

They’ve been fortunate to avoid injuries, but depth is a concern everywhere. The Redskins saw the drop-off with Landry sidelined and Reed Doughty starting in his place. There’s a big dip between several starters and second-stringers.

Coach Mike Shanahan called the defenses Week 4 performance against St. Louis the best he’d seen in 20 games in Washington. Granted it came against one of the league’s worst-ranked offenses, but it’s also something Shanahan and Haslett hope to see a lot more of when the team returns from the bye.