Even though everyone knows how important quarterback play is, and even though our eyes rarely wander away from it, it's one of the most misunderstood features of football.

Comparisons between different quarterbacks are particularly useful for revealing the confusion amongst pundits, fans, and NFL scouts, as they try to tease out which players have talent that translates to multiple systems and which are being propped up by their surroundings.

The term "system quarterback" has become a common term for denouncing players who compile impressive stats that presumably wouldn't translate if that quarterback had been playing in a different style of offense. However, that term is problematic for several reasons.

First and foremost is that the term is ultimately meaningless. Every successful quarterback who has ever played was a beneficiary of the system around him. Quarterbacks who played in systems that worked against them are generally players not lauded as all-time greats.

For instance, Notre Dame's Joe Montana was the ideal West Coast quarterback, but he was drafted in the third round. His talents did not lead to him being considered a no-brainer NFL talent. He lacked the ideal arm strength that scouts prized for the purposes of executing their pro systems. But for Bill Walsh's offense, which had not yet caught on, he was perfect.

Secondly, the term is often used as a code word for spread quarterbacks, such as Mike Leach's record-breakers at Texas Tech. Much like using the term "thug" rather than more honestly offensive language to slur Richard Sherman, people often just use "system quarterback" to criticize players who are deemed to have talent that can only shine in a spread passing offense. Meanwhile, the term is rarely used to apply to athletic quarterbacks who manage option running attacks or quarterbacks who have fairly light mental workloads while playing in allegedly pro-style systems.

Every quarterback is a system quarterback whose skills most come alive in a particular style of offense. Within a given system, there are essentially four levels of quarterback play.

Level 1: The limit-setter

Quarterbacks at this level are either too green within their systems to unlock much of the offense, or they have physical limitations that preclude them from being handed the reigns to the whole playbook.

Examples might include the quarterback who lacks the arm strength to make all the system's throws (Case McCoy), a quarterback who struggles with the complex reads that make an offense hum (most underclassmen), or a quarterback in an option attack who isn't an effective runner (John Brantley).

Level 2: The so-called "system quarterback"

A quarterback at this level has the tools and understanding to unlock multiple features within an offensive system. He might not have elite tools, but he can wield the weapons handed to him and potentially put up huge numbers. Examples include the pro-style quarterback who makes obvious decisions and throws to open receivers (AJ McCarron), the spread QB who has enough savvy and arm strength to make quick reads and accurate throws (virtually everyone Leach has coached), and the suitable option quarterback (Eric Crouch).

Level 3: The glove

Some players find themselves in situations where their skills align perfectly, forming dominant attacks. This might include players who are simply excellent at executing the tasks in their systems (Sam Bradford) or players with multiple tools that are all well-utilized (Tim Tebow).

Level 4: The transcendent talent

The guys that can make things happen that coaches would never dare to draw up on a chalkboard. This might include simply pulling the ball down and clowning defenders (Vince Young), dancing around in the backfield before finding an open target in the end zone (Johnny Manziel), or beating good coverage with the pinpoint throw that has the quarterbacks coach screaming, "NOOOOOOEYESSSSS!!" (Andrew Luck).

For most of 2013, Trevor Knight was a Level 1 guy.

In the 2014 Sugar Bowl, a Sooner quarterback named Trevor Knight (who to that point had thrown 90 passes and averaged 5.2 yards per attempt) eviscerated Nick Saban's vaunted Alabama defense for 348 passing yards on 44 throws (7.9 yards per attempt) and led an upset win over a 15-point favorite.

The question for Oklahoma's offseason immediately became: "Whoa, is Trevor Knight for real?" Because a season's worth of Sugar Bowl performances might make Oklahoma a frontrunner to win the first-ever College Football Playoff. But for most of 2013, he was a Level 1 guy, with only hints from practices or individual plays of any greater potential. Then he exploded.

So what happened? Where is he now, and what is he truly capable of?

The Oklahoma system

To evaluate a player and determine if he is a "system quarterback" requires first understanding what exactly his system entails.

The Oklahoma system is somewhat hard to define, as it's taken bits and tactics from multiple systems and integrated them into something somewhat unique. When head coach Bob Stoops arrived in 1999, he brought on Leach to install the air raid from Kentucky, which had given Stoops fits as a defensive coordinator at Florida. Leach jumped ship after a year, leaving Mark Mangino with the task of making the OU offense better on the ground. His quarterback for that championship-winning 2000 season, Josh Heupel, is now the man calling plays in Norman.

The offense has evolved from the air raid into something similarly basic but quite different in approach.

Oklahoma's primary goal is to create easy decisions for quarterbacks and one-on-one opportunities for athletes. The Sooners seek to be balanced in run and pass, and they accomplish that balance by recruiting top athletes, emphasizing execution and simplicity in schemes, and using tempo.

The optimal Sooner offense has versatile personnel who can play multiple positions, allowing them to line up in a variety of formations for runs or passes without subbing personnel or slowing down.

Ideally, an opposing team is unable to handle either the run or pass without cheating numbers over to help. The defense might load the box but then be unable to survive the solo matchups against Oklahoma's receivers. It might sit on top of the passing game in a two-deep-safety coverage, but then be unable to stop OU's run game.

Knight averaged 6.64 yards rushing on 67 attempts in 2013. Matthew Emmons, USA Today

The system requirements for a Sooner QB thus amount to the following:

1. ID where the ball should go at high tempo.

Most of an OU quarterback's mental work is done before the snap, while getting the call from the sideline or his own mental checklist and getting his teammates lined up within 15 to 20 seconds. The speed at which Oklahoma operates, in conjunction with its level of athleticism, is largely what has led to broken records under Stoops.

Much of the time on passing plays, the Oklahoma quarterback knows where he's throwing the ball before it's even arrived in his hands.

2. Make the quick reads and accurate throws to the outside.

The bubble screen is a major component to the Oklahoma attack. Coaches drill the QB to throw it well and in such a way that it leads the receiver, enabling him to use his speed on the edge against defenses often looking to stop the run:

Similarly, Oklahoma has a full arsenal of receiver tunnel screens and running back screens in which the passer doesn't have to read the defense. But he does have to learn to place the ball with as much precision as possible, so his targets can maximize the windows for playmaking before defenses swarm the ball.

Oklahoma QBs also spend a great deal of time throwing curls, hitches, comebacks, and outs on play-action rollouts:

For most of the rollout plays in OU's playbook, the quarterback throws to his first read without any real complexity. However, the QB has to be able to have some arm strength and accuracy on his ball, to get it to his receiver in time for that player to have any chance at making a move on the defense.

Quarterbacks without arm strength need not apply to the OU system.

3. Land the deep shots.

When the Sooners want to push the issue with their passing game, they'll have two main options. One is to call four verts, find the best matchup, and drop it in. The other is to take advantage of the effects of their own simplicity and tempo, causing opponents to bite hard and be susceptible to play fakes:

Oklahoma builds play fakes around its screens and run game, often utilizing the pump fake with time afforded by those runs and exhausted pass-rushers. OU will look to land knockout blows every week.

All told, mastering the Oklahoma system for a reasonably intelligent and strong-armed quarterback is a perfectly feasible proposition. So long as the Sooners don't have consecutive years in which they miss on their targeted quarterback prospects, and so long as their roster is stocked with athletes who can win one-on-one matchups, they tend to have dangerous offenses.

Trevor Knight and the Oklahoma system

Oklahoma had an uninterrupted streak of Level 2 or higher QBs from 2003 to 2012, until Jones graduated and left the coaches with a decision to make about the offense.

On the one hand, they had a full-grown Yeti disguised as a junior named Blake Bell, whom they'd been utilizing in short-yardage situations to bulldoze over hapless Big 12 defenses. Bell was listed as a pro-style QB out of high school, but he lacked the ability to make the downfield throws or the consistent accuracy outside of the hashes.

On the other hand, they had redshirt sophomore Trevor Knight, who had flashed tremendous athleticism while prepping the 2012 Oklahoma defense on the scout team.

Knight's potential earned him the starting nod early in the year. But he got dinged up when Oklahoma's coaches attempted to supplement his lack of familiarity with the system by adding read-option elements, to take advantage of his athleticism.

Eventually Knight recovered his health and took advantage of bowl practices to seize control of the offense. Then he unleashed the now legendary performance against unsuspecting Alabama in the Sugar Bowl, becoming a 2014 Heisman contender based off of one game.

Was that the real Knight? The only way to know is to check off the OU system competencies and see what we find.

1. ID where the ball should go at tempo.

Knight seemed well in control of numerous elements of the Sooner offense against Saban's defense, even occasionally going deeper into progressions than Bradford or Jones commonly had to in order to shred Big 12 defenses.

As much as Saban's struggles with the up-tempo spread are emphasized, Oklahoma didn't use lightning tempo at a particularly high volume in the Sugar Bowl, which portends to further growth for Knight and the Sooner offense in 2014.

2. Make the quick reads and accurate throws to the outside.

Knight was nails on the play-action rollouts that define so much of Oklahoma's attack. He was able to set up his receivers multiple times in the Sugar Bowl with enough zip and accuracy to exploit open field matchups:

Knight also threw some screen passes under pressure with great touch, revealing both his accuracy and arm strength:

all the difference for an offense, yet they don't always jump out to the casual observer. That ball placement often defines the difference between Level 1, Level 2, and Level 3 players. These basic skills in firing the ball where it belongs in such a way that skill players get it in stride and in time to make a move in the open field? They makethe difference for an offense, yet they don't always jump out to the casual observer. That ball placement often defines the difference between Level 1, Level 2, and Level 3 players.

3. Land the deep shots.

Knight also made some throws that easily stand out on first watch or without context. Early on in the game, he beat tight Crimson Tide coverage for Oklahoma scores, and then later he continued to make throws that eventually put the game out of reach for McCarron's offense.

Included in these throws were a few very well-placed deep balls, the kind Oklahoma loves to use to break the back of a defense with a lightning quick score.

The Sooners' inability to connect on these types of throws against Texas allowed their hated rival to bottle up their quick passing game and run game with loaded boxes and tight coverage.

Over the course of the Sugar Bowl, and again in the Oklahoma spring game, there was abundant evidence that Knight has made the leap from his role as a Level 1 limit-setter to that of at least a Level 2 system fit.

4. Something else?

However, the reason Knight was given the starting nod over Bell, and part of the reason the Sugar Bowl was so astounding, is that Knight didn't play like another OU system guy in that game. Instead, he showed some Level 4 flashes.

Ummm, what?

OU ran levels here, which gives Knight a high-low read on the middle linebacker. But Knight didn't like the way Alabama covered the routes, so he decided to aimlessly wander towards the sideline in hopes of finding something more. He pump faked and was able to bring his arm back in time to zip that pass to returning receiver Sterling Shepard.

The list of players in college football who could make that play is fairly short, and it points to a ceiling for Knight unlike what they've had in Norman before. A player who can master that offense while adding in some running ability or even Johnny Football impersonations on passing downs is one that could easily join forces with OU's talent level to form an elite team.

Three of the top four receivers from the game against Alabama -- and seven of their top nine in 2013 -- are gone. For that reason, we might not often see the redshirt sophomore at full throttle in 2014, as he was in New Orleans. However, Oklahoma has clearly found a talent that it can build around, maybe even one unlike what Sooner fans have seen in the Stoops era.

Yes, Trevor Knight is real. But he might be spectacular.