Northwestern's offense has been rooted in the same philosophy -- players, formations, plays -- since coordinator Mick McCall arrived in 2008. McCall shapes his scheme around the players first before choosing formations and plays that maximize their skills.
In the first four seasons under McCall, most of the players ended up being wide receivers and quarterbacks. Most of Northwestern's formations highlighted the wideouts and most of the plays were passes. Northwestern's offense had a clear passing lean, especially in 2009, when the Wildcats ranked 13th nationally in pass offense. The Wildcats didn't neglect the ground game, but when it came time to identify the best players, the running backs didn't make the cut.
"There's been some times in the past at Northwestern in the running back room where there was one guy, and that was it," Matt MacPherson, the team's running backs coach since 2006, told ESPN.com.
MacPherson clearly has his one guy in senior Venric Mark, who earned second-team All-Big Ten honors in 2012 after rushing for 1,366 yards and 12 touchdowns. Mark, who earned All-America honors as a return man, was Northwestern's first 1,000-yard rusher since Tyrell Sutton in 2006.
But MacPherson thinks Northwestern's options in the backfield go beyond Mark.
"I feel like we have four or five guys in my room right now that we can go win Big Ten football games with," MacPherson said. "That gives you a lot of flexibility, and it allows you to do a lot of different things. I came out of spring very pleased with the way they performed."
Mark remains the undisputed starter and will get the lion's share of the carries in the fall. He sat out most live-tackling drills this spring as a precaution, which allowed the other backs -- Mike Trumpy, Treyvon Green, Stephen Buckley and Malin Jones -- to get more reps.
Trumpy racked up 349 yards and three touchdowns on 76 carries as Mark's primary backup in 2012. Green endured a tough season with injuries and personal issues but bounced back and "had a great spring," MacPherson said. Both Buckley and Jones redshirted in 2012 but likely worked their way into the carries rotation with good springs.
"Our running back room has gotten deeper," McCall said. "We've got some guys that can play in a lot of different situations there. We've continually gotten better in that room."
Northwestern made a noticeable shift toward the run last fall behind Mark and dual-threat quarterback Kain Colter. After finishing no better than 45th nationally in rushing in McCall's first four seasons as coordinator, Northwestern surged to 19th nationally last year (225.4 ypg).
The rushing focus should continue as long as more running backs meet the first principle of McCall's philosophy. MacPherson thinks they will, and Northwestern might go with a two-back formation, which it used for 10-12 plays per game in 2012, more often this season.
"In my room, those eyes light up when they know we're going to start running the ball a bunch," MacPherson said, "and we're going to have two running backs on the field at the same time. That's something for them to get excited about. That just gives another aspect of competition, knowing that, OK, Venric may be the guy, but when we get into the two-back set, who's going to be the other guy?"
It's a question MacPherson is glad to be asking.