Giants quarterback Eli Manning managed to elude Redskins defensive end Jason Hatcher on this play Nov. 29. Washington is 25th in the league in sacks. (Toni L. Sandys/The Washington Post)

The Washington Redskins’ defensive scheme is predicated on getting pressure from its line. When that pressure doesn’t arrive, problems can arise. In Monday night’s 19-16 home loss to Dallas, the Redskins generated just one sack of Cowboys quarterback Matt Cassel — and it came early in the second quarter.

When the game turned late in the fourth quarter, Cassel’s jersey remained clean, exposing a deficiency that has haunted the Redskins (5-7). Washington is 25th in the league with 21 sacks through 12 games, and even when the Redskins have been able to get pressure, they haven’t been able to turn up the heat enough to get sacks.

“We did what we could in this game,” defensive end Jason Hatcher said. The Cowboys “did a lot of slide protection in this game. Their gaps were really close, and they didn’t really give you much opportunity to penetrate or anything like that.”

In their first season under defensive coordinator Joe Barry, the Redskins showed more blitzes than usual Monday night given the Cowboys’ personnel. Dallas was in max protection for nearly half the game, 25 of its 58 offensive snaps. Defensive end Chris Baker said the Redskins had to deal with that before — notably in the team’s first matchup against the New York Giants in Week 3, which resulted in just two hits on quarterback Eli Manning.

Against the Cowboys, it caused the Redskins to send five-man rushes and even mix in some coverage packages, called Cover 0, that left defensive backs in one-on-one matchups while they sent every other defender at Cassel. The Redskins had five plays in Cover 0, resulting in three incomplete passes, a batted ball by linebacker Ryan Kerrigan and a pass interference call on cornerback Quinton Dunbar. Overall, the Redskins pressured Cassel on eight plays in the game but hit him only once.

“We’ve got to figure out something different scheme-wise to create more pressures,” Baker said. “That’s what’s happening in the games, but we did a good job defensively. They didn’t have any big plays. We’ve just got to keep them out of the end zone on sudden-change opportunities.”

It’s perhaps the only blemish in the game from the Redskins’ defense, which held the Cowboys to 19 points, 318 yards and 1 for 9 on third downs, but it was the third game the defense has produced two or fewer quarterback hits. They got to New England Patriots quarterback Tom Brady just once in Week 9 and didn’t record a sack.

“As a defensive lineman, when you blitz a lot, that means you have to move up out of your gap, and hopefully someone else comes free,” Baker said. “I’d rather just play man-on-man, let us get our man in front of us and play ball. We don’t have to blitz to get pressure.”

The Redskins also had to account for the Cowboys’ strong dose of play-action, which causes the defensive line to freeze before attacking the quarterback. Dallas ran eight such plays, making it a difficult task for four linemen to get into the backfield against seven blockers, along with the constant threat of the running game.

“Max pro, that’s tough when they do that, but you play well with coverage and leverage,” linebacker Will Compton said. “You take away the first read, and second read there’s somebody there. . . . We had a good game plan. We’ve just got to get another turnover.”

It’s a different philosophy under Barry, who would rather receive pressure from his front four and drop seven in coverage, compared to former defensive coordinator Jim Haslett, who would send everyone. The Redskins finished 21st last year with 36 sacks.

The Redskins have also had to deal with injuries in the secondary, making it more difficult to send extra players in blitz packages. The Redskins have had to shuffle in backups in key situations, such as Dunbar as the outside corner in the nickel over the last two games, but they could attempt to incorporate more blitzes during the final four games of the season.

“We actually had a pretty good combination last week,” Redskins Coach Jay Gruden said. “We did blitz a little bit last week. We have a lot of five-man pressure, but, you know, I think the more confident we are in the secondary getting the guys healthy and guys back there that are familiar with what we’re doing, I think you might see more and more blitzes as the season goes on.

“The big thing is just making sure everybody is on the same page. With all the changeover and turnover we’ve had in the secondary, it’s hard to say, ‘Okay, we’re going to blitz six guys and leave our corners on an island or our safeties on an island.’ There’s a combination there. Hopefully we’ll keep them guessing.”