CLEMSON –While much of the focus this spring has centered upon Clemson’s challenge of finding three new starting offensive linemen the defensive line has also has three vacancies. And it was the defensive line which was the strongest unit on a defense that struggled through much of the 2011 season.

Clemson graduates defensive end Andre Branch and tackles Brandon Thompson and Rennie Moore. Branch led the Tigers in sacks (10.5) and tackles for loss (17) last season and Thompson was dominant in the season’s first half. Defensive end Malliciah Goodman is the only returning starter and only upperclassman along thedefensive front. Rebuilding the line is the first major challenge facing new coordinator Brent Venables who has been tasked with improving a defense ranked 71st in total yards allowed (394 yards per game) and 84th in rushing yards allowed (176.86 yards per game) last season.

“It all starts up front, it’s not earth shattering news,” Venables said. “We’ll try to get them a bunch of snaps to make of for a lack of experience. ... Those guys have shown an ability to hold their own.”

Sophomores end Corey Crawford, and sophomore defensive tackles Tavaris Barnes and DeShawn Williams all figure to be major contributors after filling reserve roles last season. Freshmen like four-star defensive tackle Carlos Watkins and four-star defensive end Shaq Lawson are expected to provide an immediate impact.

Venables has indicated the season opening depth chart will not be determined by spring performance but first impressions will be formed.

“Things are wide open,” Venables said. “We will judge by a body of work. It’s one thing what you’ve done in the past but it has zero to do with what you do in the future. … I want guys to know they have a fighting chance that there’s an evaluation process going on every day.

“Guys are making progress I think we’ll have guys that can more than hold their own. I like the athleticism, the strength, the ability to play with leverage.”

Before he was dismissed, Kevin Steele was encouraged by the potential of the 6-foot-1, 290-pound Williamsand he also raved about the 6-foot-6, 270-pound Crawford’s maturity.

One player who has impressed coach Dabo Swinney early in spring practice is Barnes. Barnes switched between end and tackle in his first two years on campus but the redshirt sophomore seems best suited to be a Rennie Moore type of undersized tackle.

“He’s one of those guys I’m really pleased with after five practices,” Swinney said. “He’s been very, very solid. If he’s not a very good player then we are probably not going to be a very good defense. I think he’s turning the corner, buying in to what it takes to be a good player. When all is said and done he could be a special player.”

Has Barnes, a former four-star prospect, been motivated by the questions surrounding the young defense, the criticism following the Orange Bowl collapse?

Said Barnes: “Oh, yeah.”