Two of those experiments have turned into solid performances from a pair of returning players who had struggled previously.
Wide receiver Wes Lyons has found success this spring after moving from the boundary into a slot receiver position.
Part of that success is due to the fact the senior is finally healthy after dealing with a series of injuries in the earlier part of his career. Mullen credits the other part to Lyons' move to the slot.
"He's a kid I think that just matches up in the slot a little bit better," Mullen said. "It's been a lot of fun for us to watch him have a good spring."
The North Braddock, Pa., native's success in the slot begs the question why bigger targets aren't seen more in that role as opposed to the smaller, quicker receivers that typically have played there in the past.
"You don't see 6-8 in college football anywhere," Mullen said. "But if you look at a lot of teams, that is the tight end position. The slot is the tight end position, just in a different personnel grouping. That's what you see a lot of other football teams doing."
After WVU struggled mightily in that area last season, Mullen and company have hope that Clarke could provide some much-needed assistance this year.
Clarke made an impression in the Mountaineers' first scrimmage, scoring three touchdowns in goal line drills near the end of the session.
"I like Ryan Clarke and what he's given us," Mullen said. "He's another kid that we weren't able to use last fall, but this spring has given him a chance to do it this fall if he continues to get better."
While the redshirt freshman didn't have the same type of success in the team's second scrimmage Wednesday, gaining only four yards on 11 carries, he did reach the end zone again in goal line work.
While the raw numbers in terms of yardage gained by a bigger back may rarely off the page, it's the ability to gain a yard when it's needed that characterizes the player's success or failure in the role of a short-yardage runner.
That's one of the reasons for optimism Mullen has found in Clarke's play this spring.
"That helps me sleep a little bit better knowing there's a 250-pound man back there that can get us a yard," Mullen said. "We're getting in the huddle and bursting out of it quickly, showing a couple of different alignments and giving it to a little bit bigger kid. I think it's going to be more difficult for defenses to stop us."
Mullen and the rest of the West Virginia staff are aware that even the best running back can gain yardage only if the line in front of him can create lanes to run through.
Stalwarts like departed center Mike Dent and left tackle Ryan Stanchek are no longer in Morgantown. In their stead, the unit has rallied around each other as it attempts to improve under position coach Dave Johnson.
"I'll tell you one thing I like about our O-line right now -- there really seems to be a sense of togetherness in that room," Mullen said. "I can't pinpoint it, but I really have a good feeling about that group and how they're gelling and meshing."
"We've just got to find some depth," Mullen said. "I'm really excited about these kids. That room is a really healthy place to be right now."
That line will also be tasked with blocking for a "new" starting quarterback for the first time in four seasons, as senior Jarrett Brown finally has his opportunity to lead the West Virginia offense.
Brown has had a largely successful spring while running an offense that has included fewer designed quarterback runs and a bit more conventional pocket passing than it did a season ago with White taking snaps.
"It's not because JB can't run, but it's the depth," Mullen said. "You felt good about Pat running the football last year because you knew you had an experienced backup.
"Until I feel good about who our backup quarterback is, I'm going to make sure I take care of (Brown) a little bit. You don't want to get him hit if you can help it. Don't get me wrong -- he's a really good runner, so we're going to do it. But how much we do it will depend on the depth at the quarterback position."
Mullen's security with that depth will depend on the play of current backup Coley White as well as incoming freshman Geno Smith.
The coordinator said Smith, who attended all of West Virginia's practices while he was on spring break last week, will have every chance to earn the No. 2 slot behind Brown come fall.
"I feel really good about who the depth at backup, but I've just got to hone in on who that guy is this fall," Mullen said.
With Smith headlining a talented freshman class that will arrive this fall, Mullen will look to quickly teach that crop of players his system and see who can contribute immediately.
"It's way too early to tell (which true freshmen might play)," Mullen said. "I hope they all can come in and help us. But I hope, more importantly, that the older guys who understand what we're doing are the guys we're playing with."