One of Bronco Mendenhall’s first moves as Virginia head coach was to scrap former coach Mike London’s 4-3 defense and instead implement a 3-4 alignment. Assistant coach Nick Howell gained the title of defensive coordinator, but it was Mendenhall calling plays from the sideline.As expected, the transition wasn’t the smoothest in the world. The Cavalier defense by and large lacked both the depth and size on the defensive line to generate consistent backfield pressure. Further, Mendenhall did not have dynamic outside linebackers to set the edge or force the quarterback up in the pocket. Virginia surrendered 33.8 points per game, ranking 99th out of 128 FBS teams. The Cavaliers also ranked 93rd in total defense — giving up 446.6 yards per game — and 88th with only 17 takeaways.Mendenhall’s unit will likely struggle again with personnel in year two, but Virginia does return two All-ACC first teamers in safety Quin Blanding and linebacker Micah Kiser. For the Cavaliers to improve in 2017, those two will have to lead the charge.After examining the offensive depth chart last week, former sports editor Robert Elder takes a look at Virginia’s spring defensive chart. Defensive Line Starters: Jack Powers, Juwan Moye, Eli HanbackKey Backups: James Trucilla, Christian BaumgardnerVirginia is currently very thin on the defensive line in practice. Last season’s nose tackle Donte Wilkins graduated and 2016 starting defensive end senior Andrew Brown is missing this spring due to injury.With no sacks and just two tackles for loss last season, Wilkins did not have quite the strong performance many anticipated. Still, his graduation leaves Virginia dangerously thin on the defensive line. Sophomore Juwan Moye is starting at nose this spring, but the former high school linebacker is small for the position at 275 pounds. Both he and his backup — sophomore James Trucilla — combined for just seven tackles last season.Brown flashed at end a year ago with six sacks and 13 tackles for loss, but he was hampered by injuries late in the season. Both Powers — who was formerly an offensive lineman at Arizona State — and sophomore Eli Hanback should show improvement.Outside LinebackerStarters: Chris Peace, Malcolm CookKey Backups: Eric Gallon, Gladimir PaulPeace started all 12 games last season recording 6.5 tackles for loss and two sacks. Mendenhall will look for an increase in production from him in year two at linebacker. Meanwhile, Cook missed last season due to myocarditis — a heart disease. He impressed in practice last year, but he is still small for an outside linebacker at 6-foot-1.After 2016 freshman Matt Terrell transferred in March, the Cavaliers have little proven depth behind Peace and Cook.Inside LinebackerStarters: Micah Kiser, Jordan MackKey Backups: C.J. Stalker, Jahvoni SimmonsIn 2016 Kiser led the ACC with 134 tackles. He also pitched in 10 tackles for loss, 6.5 sacks and an interception. After Landon Word transferred following a promising freshman season, sophomore Jordan Mack will transition to the inside after starting nine games at outside linebacker last season.The Cavaliers should have depth here with a pair of former four-star recruits as backups in junior C.J. Stalker and redshirt sophomore Jahvoni Simmons.CornerbackStarters: Tim Harris, Bryce HallKey Backup: Germane CrowellFifth-year senior Tim Harris appeared in just two games last year before injuries derailed his season. Then-freshman Bryce Hall made seven starts in his absence, snagging two interceptions, both against Duke.Junior Myles Robinson started Virginia’s first four games but was later sidelined with injuries and has since switched to safety. Early-enrollee freshman Germane Crowell was Virginia’s highest rated recruit in the 2017 class and could earn time as well.Darious Latimore, who was suspended for a violation of team rules and later tore his ACL in 2016, could provide depth if healthy.SafetyStarters: Quin Blanding, Juan ThornhillKey Backups: Nick Grant, Chris Moore, Myles RobinsonAfter forgoing the NFL draft, Blanding returns for his senior season having already collected a plethora of All-ACC honors. Still, despite already ranking No. 9 all-time at Virginia with 358 career tackles, Blanding still sometimes struggles in coverage.Thornhill played cornerback last year and led Virginia with three interceptions. He has gained weight to play safety in the base defense this season, and he could still play nickel corner in sub-packages.Redshirt freshman Nick Grant has filled in at safety in practice when Thornhill slides to corner, and sophomore Chris Moore provides depth after playing in 11 games last season.TakeawayThe 3-4 defense is a difficult scheme for college teams to play. To be successful, teams usually need three starting defensive linemen each weighing around 300 pounds and several backups to rotate in. And at outside linebacker, the best teams have dynamic pass rushers who can also set the edge against the run.Such players are generally hard to recruit out of high school, and Virginia certainly didn’t have enough impact players last season. While the outside linebacker unit might improve with Peace’s development and Cook’s return to health, the defensive line will be even thinner in year two.Blanding and Kiser will again be expected to lead the defense, but that might not be enough though to drastically improve Virginia’s performance.Robert Elder was the 127th Sports Editor for The Cavalier Daily. He can be reached at email@example.com or on Twitter at @R_F_D_E.