College football is changing. Yes, the game will finally feature a Playoff in 2014. True, issues regarding the compensation of athletes threaten to overhaul the entire structure of the NCAA.

But if you were to ask a longtime defensive coach like Manny Diaz where the sport is heading, he'd point you to a signature moment in the most thrilling game in recent memory: Auburn's victory in the 2013 Iron Bowl over mighty Alabama.

But Diaz wasn't as struck by the "Kick Six" touchdown that sealed the deal for the Tigers, nor the budding Saban-vs.-spread rivalry. Instead Diaz zeroes in on a play by Auburn quarterback Nick Marshall, one ending 31 seconds before Chris Davis' 109-yard game-winner.

"It's the most significant thing to happen to college football," the 17-year coaching veteran says. "The most important play of last season was the touchdown that tied the game at 28."

The play in question started out as a standard zone-read play, one Auburn had been running the entire season. It was at this moment that Gus Malzahn's offense brought football's future to the biggest stage.

The workings of the play are standard. It kept with what's become familiar to even NFL fans ... up until the end. The offensive line started to block for an inside zone play. As far as the linemen knew, they were blocking straight ahead for another Tre Mason run. The fullback, Jay Prosch, arced around the unblocked defensive end to provide a lead block on the edge for Marshall, in case the quarterback got a "keep" read. The addition of a lead blocker on the edge for the QB has caused enough trouble for college defenses, but that wrinkle is one Alabama already knew was coming. Marshall saw the defensive end stay inside, giving him the sign to keep the ball and follow Prosch's block on the edge. This is where things got interesting. Marshall made an additional read to determine whether his X receiver, Sammie Coates, was being covered or not. Since both the free safety and corner came up to stop the quarterback keeper, he awkwardly pulled up and tossed a hitch route to Coates. Touchdown. The Iron Bowl is tied. College football has been changed. To successfully execute that play, Marshall had to untuck the ball from his left arm and pull up to fire it downfield. His line was close to being more than three yards downfield, which is a violation of the NCAA rules on passing plays. Auburn didn't typically call the play with this option attached in 2013, although it's a good bet they might do so more often in 2014.

What is it?

But that was only the surface of what's becoming possible with plays like this one, which are being dubbed pop pass plays both for the quick-hitting throws and as an acronym: play-option pass. Have you ever noticed the glitch in football video games in which you can run your QB at the line of scrimmage and then throw it over the heads of defenders if they rushed up to stop you from scrambling for easy yardage? With pop plays, that nightmare has become a reality. One successful Texas high school head coach indicated he's rebuilding his offense around this tweak on the option. "On any given run play or down, the QB has a pass read as well," he said. "Your QB better be a sharp kid, or all this is for naught. If you're the QB, it's like playing 'NCAA Football' on the Xbox. You can always alter the read, route, or play." And Auburn's hardly the only college team to use it. Other coaches like Arizona's Rich Rodriguez, Ohio State's Urban Meyer, and Kansas State's Bill Snyder have already made pop plays a featured part of the offense. Tim Tebow used it at Florida and even as a gadget in the NFL. Meyer expects the number of teams running it in 2014 to double. Michigan discovered its deadliness in the Buffalo Wild Wings Bowl:

This is Kansas State's quarterback draw/pop concept, likely the first of many such concepts to define the new Jake Waters version of the always-innovative Bill Snyder offense. The draw play is a staple in the KSU attack, both the classic RB lead draw from under center and the more modern versions of quarterback draw. Snyder and offensive coordinator Dana Dimel have now expanded the play to include second-level reads by the QB: In these versions, the quarterback reads the middle linebacker to determine whether to run behind the lead block or throw the quick pass. Everything the middle linebacker has ever learned about football tells him to charge and meet the lead block as close to the line of scrimmage as possible, preventing a crease from forming for the runner. But during pop plays, that aggressive instinct is turned against him. Maybe the fullback is going to feign a block and run past the linebacker, becoming a receiver. Maybe a tight end or slot receiver is going to run into the space that the linebacker is responsible for in pass coverage. The quarterback inches toward the line and makes a quick read. Is the linebacker attacking? Throw the easy pop pass over his head. Is he hanging back in hesitation? Run through the crease. If the defense tries to move in that sam linebacker (S) to help stop the play, KSU will run this same concept with the option to throw a quick bubble out to the slot receiver the sam is supposed to cover. Involve the cornerback in the run game, and they'll throw a slant to the now wide-open Tyler Lockett on the outside. One can only imagine what they'll have come up with after a full offseason with an established quarterback in this new system. Under Hugh Freeze's direction, Ole Miss is making full use of these tactics, with Dr. Bo Wallace writing out prescriptions for confusion at every turn. Here's just one example of how the Rebels have used it to form some cohesive concepts.

In this version, Ole Miss attached a quick route up the seam by the tight end to an inside zone play. Spread-option teams like the Rebels are starting to add these pop reads to all of their running plays. It's a simple matter of finding easy throws that put a defender in run-pass conflict, meaning an aggressive fill against the run results in a window to an open receiver. Linebackers and defenders who have been taught to read linemen for whether to play the run or pass are left in a world of hurt. They're forced to turn around and hope the next level of the defense has picked up the receivers they were supposed to cover. "Every defensive coverage has a deep level, an intermediate level, and a no-cover zone," says Penn State defensive coordinator Bob Shoop. "[These pop plays] are trying to create separation in the intermediate level."

How do you stop this?

What surely irritated Nick Saban the most about Marshall's touchdown in the Iron Bowl was that Alabama actually had the play accounted for on the chalkboard. The boundary side (the side closest to the sideline) of the Tide defense, which was targeted by Marshall and Coates, had a costly assignment bust that made the score possible. Because of vertical passing plays that have become mainstays, the defense always has to have a defender to account for a potential deep route. One of either cornerback Cyrus Jones or free safety Ha Ha Clinton-Dix needed to be responsible for staying on top of a vertical route by Coates, while the other needed to attack Marshall. They both went after Marshall. Easy score. That's a consequence of the modern spread-option and the addition of vertical throws to run plays. Errors or missed tackles have dire consequences when defensive players are even more isolated and spread out. "What they have done is separate the defense," says Diaz. "Slants are now a one-on-one tackle, because the pursuit of your defense is gone. You better have 11 guys that are excited about tackling now." Defenses have to give enough players "pass-first" assignments to prevent easy touchdown passes, while the rest of the defense is free to respond to a running play. Yet even if the defense is sound with players assigned to stop the run or pass, they've lost team pursuit. With half your defense stopping a run that isn't coming, your spaced-out secondary no longer has much help from the linebackers in stopping a quick throw to Tyler Lockett on the run. That's pretty tough to consistently stop. Due to the unavoidable constraints of handling these offensive attacks, nearly every team is now basing around quarters and cover 3 (four and three deep zones, respectively), using pattern-matching principles to ensure tighter coverage and no easy windows to throw through. Blitzes called on potential pop-pass downs have to be man blitzes. And even zone blitzes have been adjusted to include man-coverage principles, to avoid getting burned by easy throws against conflicted defenders. Every call in the defensive playbook has to be "option-sound" now. With quarters, cover 3, blitzes, and most every call that isn't Tampa 2, having great cornerbacks who can play without help on the sideline is a must. Having stout players up the middle who won't be pounded if isolated against the run game doesn't hurt either. Recruiting strategies are going to continue to evolve to prepare for spread-option teams on the schedule. Given the need to match up in pattern-matching coverage, which ends up looking like man coverage, and the need to make tackles in space, the resulting need is for defenses to get even faster. "You often divide a defense into three categories," says Shoop. "Cornerbacks, the [middle players: mike linebacker and defensive tackles], and the alley players [ends, outside linebackers, and safeties]. With the alley players, it's like going to a Cold Stone Creamery: it's all the same guy, just in different sizes. Maybe the mike and the tackles are the only guys who don't run faster than a 4.8. Everyone else is an athlete." Because the quarterback is on a short clock to make a read and deliver the ball, the defense has to present an element of disguise. If the offense doesn't know which player will be the one to read, it can be difficult for the QB to react quickly enough to punish that player. Teams with versatile, fast defensive backs and linebackers can mix around which of Shoop's "alley players" have which responsibility. The advantage of blitzing with one-deep safety coverage is the defense can lock everyone up in man coverage, control the line of scrimmage with wide paths by the outside blitzers, and still have help over the top. There aren't many run-pass conflicts, and while there are still one-on-one matchups for the receivers, there are also one-on-one matchups for the pass rushers.

"To counter the man blitzes effectively, you must have a stinger at outside receiver. Otherwise, checkmate," noted our pop-wielding Texas high school coach. Using quarters coverage has the advantage of keeping more defenders in off alignments. This allows the defense to keep more eyes on the ball and to mix responsibilities. The defense has a few options in quarters about which players stay deep and which players eye the run. It can rely on cloud coverage, with the safety deep and the corner stepping up to force the run, a call more common when there's only one receiver out wide. This is the most solid run-stopping option, if the corner can tackle. Then there's buzz coverage, a common call against dual wide receivers, which asks the outside linebacker to play the edge and force runs inside rather than playing a gap between the tackles as he normally would. Because you are removing a linebacker from the box, inside runs become more difficult to defend from this call. Then there's sky coverage, a call useful against either one or two removed receivers, in which the safety is responsible for forcing runs inside while the corner makes sure no one gets deep. The safety has to be careful not to come up until he's sure the slot receiver isn't running past him. Cover 3 with pattern-matching is another useful defense that can change up which players take on run or deep pass responsibilities. The main difference from quarters is that by dropping a safety closer to the line of scrimmage, it allows the mike and will linebackers to stay in the box while more coverage-savvy players roam the flats and play man coverage against the better receivers. The weakness in many cover 3 calls is that the "force players" defending the edge against the run are easy to put in run-pass conflict, since they must also defend the slot receivers. Perhaps the best combination is for a defense to master an option-sound blitz package along with either a versatile quarters package or a versatile cover 3 package. Veteran defenses with upperclassmen at the safety or linebacker positions have the greatest advantage, since they can potentially master multiple calls while remaining option-sound in each. In the short term, these are the tools defenses have for stopping packaged plays, but everyone on that side of the ball is waiting for the innovative breakthrough that will allow for consistent 17-13 victories once again. In the meantime, holding offenses to field goals and a few stops is about all that can be expected, even from a great defense, when playing the more talented pop teams who can consistently get one-on-one matchups. Diaz: "If their [isolated player] is Tavon Austin or Kendall Wright or Tevin Reese? It’s going to get really hard. It’s like calling a motion offense in basketball: your QB just makes you right."

What's next?

Defenses better hope that innovation strikes Saban or some young defensive coach soon, because pop plays are still in their infancy. Many more developments and adaptations are coming down the line. Teams are still working out which pass plays can be incorporated, with deeper throws starting to find their way to the testing floor. Oklahoma showed off a zone running play with a post and fade route attached in their spring game: