Duke’s Conner Vernon was the latest wide receiver to have a big day against Demetrious Nicholson and Virginia’s young secondary. (Chris Seward/Associated Press)

Virginia Coach Mike London knew this season would be a challenge for a defense breaking in a host of new starters. But after watching near interceptions sail through defender’s hands and fumbles slip under their fingertips at an alarming rate, the former defensive coordinator has just one phrase to describe this unit: “mind-boggling.”

Since starting the regular season with two wins, not much has gone right for the Cavaliers (2-4, 0-2 ACC), who enter Saturday’s game against Maryland (3-2, 1-0) on a four-game losing streak. There’s also no getting around that in those defeats, Virginia has given up more than 40 points three times.

The Cavaliers are currently on pace to allow more points per game than they have since 1975, a strange distinction considering this defense is middle-of-the-pack in most ACC statistical categories. London believes it all goes back to the turnovers — or lack thereof.

Virginia currently has the worst turnover margin in the country (minus-12), and only Buffalo has forced fewer turnovers (two) than the Cavaliers this year (three). Combined with the team’s own penchant for turning over the ball — Virginia has 15 this season — London calls the giveaways — or lack thereof — “the biggest culprit” for a defense that is still searching for an identity at this point.

London realizes that to cover up the defense’s weaknesses, there needs to be shortcuts in terms of getting off the field.

“If you look at last year, you can just see more plays being made defensively from the older guys,” senior linebacker LaRoy Reynolds said. “We just got to make more plays when they’re given to us, when the opportunity is there within the scheme of the defense. We have to be able to make those plays, be able to get our offense back on the field.”

Despite that, the Cavaliers have had a few encouraging moments, like holding Penn State to 16 points despite the Nittany Lions receiving prime field position courtesy of four Virginia turnovers and keeping Louisiana Tech’s prolific offense to less than 400 yards last month. But too often, they’ve been susceptible to the explosive play.

At Georgia Tech, the Yellow Jackets scored two touchdowns of 70 yards or more on the first three plays of the game.The next week against TCU, wide receiver Brandon Carter scored a touchdown on a 68-yard reception on its first series of the day. Facing Duke this past Saturday, Virginia’s defense allowed four touchdowns of more than 30 yards.

Only North Carolina State has given up more plays of 40-plus yards among ACC teams this season.

London felt part of the problem at Duke was fatigue in the second half, and he has made it clear that the defense will utilize more of its younger players going forward, especially on the defensive line. That, though, will only add to the problems that have lingered since the preseason began.

“To me, we’re young at certain positions and it’s a growing experience,” defensive line coach Jeff Hanson said. “At those positions we’re learning and basically, we’ve given up some big plays because of inexperience.”

In particular, the secondary has been a focus of much angst since last season ended. The Cavaliers have three new starters in the defensive backfield and don’t rely on any upperclassmen. Duke wide receiver Conner Vernon, who caught seven passes for 93 yards and two touchdowns last week against Virginia, said this week his coaches made it a point to mention the Cavaliers’ lack of experience in the secondary during preparation.

Too often this season, Virginia safeties Anthony Harris and Brandon Phelps — both of whom are in their first years manning the position — have bitten on pump fakes and play-action. It has left sophomore Demetrious Nicholson, the team’s lone returning starter in the defensive backfield, on an island at cornerback, which has proven to be a hit-or-miss proposition.

Cornerback Drequan Hoskey said this week the chemistry early on was “a little off” in the secondary because all the starters were basically brand new. But even as they struggled to create any turnovers at the start of the season, Harris noted there was a fun-loving internal debate over which defensive back would come up with one first.

Now that the issue has become a full-fledged problem, though, Hoskey said they try not to bring it up. After all, the coaches are harping on it more than anyone.

“When the ball’s in the air, you just can’t let those opportunities slip away,” Hoskey said. “It kind of hurts right now, but we’ve just got to keep moving on. You can’t dwell on these losses.”