Before visions of Teddy Bridgewater and other rookie sugarplums start dancing in their heads, NFL teams need to sort through the quarterbacks they already have.

Lots of "mystery quarterbacks" earned long looks as starters this season: undrafted rookies, practice squad refugees, clipboard lifers and ambassador-class frequent flyers. Some won a few games. A few are young enough to be taken seriously as prospects. But were any of them really good? And just how good is good? There's a difference between proving you are a capable backup and earning the keys to a franchise. Are Case Keenum or Bryan Hoyer good enough to groom a rookie, compete with a rookie or eliminate the need for a rookie altogether?

The following scouting reports are built from film study of hundreds of pass attempts (plus sacks, scrambles and keepers) by this season's most mysterious mystery quarterbacks. To simplify final evaluations, I modified the Bang-Marry-Kill holistic scoring rubric (the most influential evaluative tool of the 21st century) into the Backup-Maybe-KO system. Backup means that he has proven that he can be a second-string NFL quarterback for a good team; that's a promotion for many of these guys. Maybe means he could still develop into a starter. KO means please, please, please get this guy an offensive coordinator job at some FCS college before we are forced to watch him throw again.

Before you ask: Nick Foles has graduated from this exercise, having proven his full-blown starter capability. Josh McCown has also graduated, having earned backup quarterback jobs until his 40th birthday. Jeff Tuel and a few others never got a real shot. The big-name rookies will get their own article later in the month.

And what is the SATS test? SATS stands for size, arm, trust and speed, the four basic skills of an NFL quarterback. Three of them are self-explanatory. "Trust" is the lone intangible, but it is not that hard to evaluate in backup quarterbacks: If an undrafted rookie hangs on the practice squad of a demanding coach for a year or two, and he is not that coach's nephew, then he clearly possesses workplace readiness skills.

Case Keenum, Texans

Who is He? Houston hometown hero and one of the most prolific passers in NCAA history. Overlooked in the 2012 draft because he had a long injury history and flunks the "size"portion of the SATS test. Keenum went from clipboard-bearing developmental project to starter when Matt Schaub imploded and the Texans saw little purpose in giving backup T.J. Yates an extended look.

What He Does Right: Very good passer on the move. Looks downfield for open receivers when scrambling. Comfortable rolling and throwing to either side of the field. Throws deep with distance and accuracy. Will stay in the pocket and deliver passes against a heavy rush. Threads some needles. Runs well enough to buy time and can be an occasional bootleg-option threat.

What He Does Wrong: Height is an issue. Reverts to a three-quarter-armed passing motion at times, resulting in some batted passes and a loss in accuracy. Midrange passes over the middle can be an adventure, arriving too high or sailing behind his receivers. Has too much faith in his arm at times and will throw off his back foot under pressure. Has too much faith in his legs at times and will attempt ill-advised Randall Cunningham scrambles (see the Jaguars game). Like many short quarterbacks, Keenun drifts in the pocket to find passing windows, a habit that can cause problems for pass protectors and limit his ability to progress through reads.

Summary: Keenum is a "slow clock" quarterback whose best and worst decisions occur late in the play, when pass routes have developed and the pocket is collapsing. For every downfield throw on the run or rollout bomb to Andre Johnson, there are several plays where Keenum takes a sack, gets hurried, or delivers a throw that should have arrived a split-second sooner.

The Texans' play-action style suits Keenum because it is full of seven-step drops, rollouts and slow-developing pass routes. It is not clear whether that will be the Texans offensive style next year, or how well Keenum would adapt to more of a read-plant-throw system (though he put up big numbers in a quick-trigger system in college). Like many small "pesky pepperpot" quarterbacks, Keenum can be effective in short doses, but low completion rates (54.2 percent) and waning big-play capability in recent games may be signs that the league is figuring him out.

Decision: Maybe. Keenum can definitely stick as a 10-year backup, but there may be more to him than that. He does enough well, and has enough upside, to merit starter consideration.

Brian Hoyer, Browns

Who is He? A 28-year old former Tom Brady backup who became a hip dark horse starting candidate among the cool NFL scouts during brief stints in Arizona and Pittsburgh. Cool-scout-turned-Browns-executive Michael Lombardi gave Hoyer a two-year contract, and Hoyer emerged from the Brandon Weeden-Jason Campbell morass to lead the Browns to two early-season victories before suffering an ACL injury early in his third start.

What He Does Right: Mechanically and fundamentally sound, for the most part. Passes the SATS test, with enough arm strength and escape ability. An accurate short-to-midrange passer with good touch. Decisive underneath passer who anticipates receivers getting open, checks down to second and third targets, and finds soft spots in short zones. Executes a full playbook and can make pre-snap adjustments. Led critical fourth-quarter drives against the Bengals and Vikings and looks comfortable in two-minute and other high-stress situations.

What He Does Wrong: Lacks a feel for zone coverage and will throw directly into a linebacker or safety's zone. Very inconsistent eye discipline: Hoyer sometimes does a great job of scanning the field and looking off safeties, but he often stares down his receiver. He led safeties directly to Josh Gordon on a few downfield passes against the Bengals, narrowly avoiding interceptions. Pats the ball before throwing, leading to some late balls. Will hang in the pocket too long and take sacks, though a bad offensive line often left him with too little time to accomplish anything.

Summary: There's a reason scouts love Hoyer: He looks smooth when throwing the ball, places passes right on his receivers' hands and does all the technical stuff that folks who are into biomechanics simply adore. Those attributes are true, marketable skills. But Hoyer was also born in the same year as Matt Ryan and Joe Flacco and has started just four career games, including one in which he threw four passes before getting seriously hurt and another in which he threw three interceptions. Like another well-known Browns prospect, Hoyer is at his peak, so it is silly to talk about him "developing" out of many of his bad habits.

The Browns, it must be pointed out, have an ugly track record of overvaluing players of his type (see: Derek Anderson, Kelly Holcomb, Brandon Weeden). It is not fair to saddle the current Browns administration with the sins of the past, and Hoyer is just good enough to start for a year while an organization grooms a rookie. The Browns just have a decade-plus history of falling in love with the journeyman and short-circuiting the whole grooming process.

Decision: Backup. He would earn a "Maybe" if he was 24.

Scott Tolzien, Packers

Who Is He? An undrafted 2011 rookie from Wisconsin, Tolzien caught Jim Harbaugh's eye and stuck as the 49ers' third-stringer for two years. The Packers grabbed him when they woke up one September morning and realized they forgot to acquire a backup quarterback. Two months later, Tolzien was in the lineup and enduring some tough losses at the hands of the Eagles and Giants.

What He Does Right: Passes the SATS: fine arm, enough mobility (see: spin move for touchdown versus Vikings) and whatever gumption it takes to impress both Harbaugh and Mike McCarthy. Throws a fine deep ball: accurate over the middle 15-25 yards downfield, good placement on long sideline throws. Hits short receivers in stride. Looked decisive, making tight throws and calling adjustments at the line, before things started to go south for him late in the Giants game.

What He Does Wrong: Started to deteriorate after a few interceptions in the Giants game, and was in danger of falling apart before getting benched against the Vikings. Strictly a "script" quarterback at this point in his career, with little ability to look beyond his primary read. Does not diagnose coverage well and will make drive-killing mistakes. By the Vikings game, Tolzien was underthrowing deep passes he completed in earlier games and throwing behind receivers he would have connected with against the Eagles and Giants.

Summary: Tolzien was not in camp with the Packers, so it is no surprise that his comfort in the offense waned quickly. In fact, what he accomplished on short notice was surprising: The Packers scaled their scheme down, but not by much, and Tolzien moved the ball well early in all of his starts. He is hard to evaluate given the unique circumstances. He may be a much more effective quarterback given a full offseason of preparation.

Decision: Backup. The Packers should consider locking him down as Aaron Rodgers' caddie so they don't spend next August goofing around with Vince Young.

Matt McGloin, Raiders

Who is He? An undrafted rookie from Penn State was impressive enough in training camp to leapfrog over Matt Flynn and Tyler Wilson on the depth chart to become Terrelle Pryor's backup. With Pryor injured, McGloin engineered a win over the Texans and kept the Raiders in the game against the Titans and Cowboys. Pryor is healthy, but his play began unraveling during losses to the Chiefs, Steelers and Eagles, so the Raiders are sticking with McGloin as the starter for the immediate future.

What He Does Right: Passes the SATS test. Finds open receivers over the middle of the field. Uses his eyes and pump-fakes well to freeze safeties and help receivers get open. Shows some pocket presence and ability to step up to buy time. Frequently puts deep sideline passes on his receivers' fingertips.

What He Does Wrong: Footwork is poor, and overall throwing mechanics are inconsistent. Steps every which way when throwing. Varies his delivery, but not in a good way. The mechanical issues lead directly to accuracy issues: short passes sail behind receivers or arrive like sinkerballs, deep touch is inconsistent, and too many passes are batted at the line of scrimmage. Appears to push the ball when throwing downfield.

Summary: The Raiders designed their offense for an inexperienced quarterback, and McGloin does an adequate job playing within the system: mixing screens with short rollout passes, taking the occasional downfield crack against man coverage, jogging out to play receiver on direct snap plays. The Raiders offense is not designed to force him to make multiple reads, and McGloin does a fine job making the decisions he is required to make. His mechanical defects may prove to be hard to correct -- there are an awful lot of them -- and a quarterback hoping to survive as a midrange talent with savvy decision making skills needs better precision that McGloin will ever have while stepping sideways and throwing three-quarter armed.

Decision: Backup. The Pryor-for-McGloin decision comes down to a potential franchise quarterback with bad habits versus a player with a journeyman skillset and slightly fewer bad habits. Like the Browns, the Raiders have to think long and hard about a decision that keeps them on the treadmill.  

Thad Lewis, Bills

Who is he? A former Duke quarterback (please don't stop reading) who went undrafted in 2011 but made enough of an impression to hang around the Rams and Browns practice squads. Earned a few starts for the Bills when their other quarterbacks started drumming for Spinal Tap. Helmed a win over the Dolphins and kept the Bills in the game against the Bengals and Saints.

What He Does Right: A SATS All-Star: big guy, big arm, runs well, shows up to work and play. Throws hard enough to complete out-route passes, beat coverage on intermediate routes and lift the defensive lid on deep throws. Knows his role and will check down instead of taking a risk. Runs like a fullback and can break a tackle to escape the pocket.

What He Does Wrong: Fumbles. Has a slow clock in the pocket, takes too many sacks and is often in the act of throwing when hit. Also fumbled on an option run in the Saints game. Has an inconsistent delivery and a bad habit of throwing over the middle while falling backward under pressure. Very scatter-armed on short passes; leads his receivers too far on simple throws.

Summary: Lewis offers enough arm talent, leg talent,and game management ability to allow a team to run its full offense with him at the helm. At the same time, his erratic accuracy and slow clock will always be liabilities. It's a fine skillset for a backup, which is why Lewis keeps popping up on rosters. He may look like a different player if he makes some spot starts on a good team given a full offseason of preparation.

Decision: Backup. Lewis has earned a promotion from practice squader to Derek Anderson-style career No. 2 quarterback.

Kellen Clemens, Rams

Who is He? Thirty-year old failed Jets prospect, buried on their bench and forgotten by the outside world after a long look in 2007. Resurfaced with former Jets coordinator Brian Schottenheimer in St. Louis. Took over when Sam Bradford suffered a season-ending injury; helped the Rams beat the Colts and Bears and stay competitive against tough divisional foes.

What He Does Right: Knows what he is doing. Will look off safeties and check down. Doesn't take foolish risks. Will step up and move around the pocket at times. Has not been helped by his receivers, Jared Cook in particular, who drop many catchable (if imperfect) passes. 

What He Does Wrong: A borderline SATS case with adequate arm strength, a wisp of foot speed and the complete confidence of exactly one NFL coach. Very inaccurate. Has awful ball placement on some easy throws: will force receivers eight yards away to reach for passes, submarines midrange throws over the middle and fires 85-mph fastballs on dump-offs. Lacks feel for the blindside rush and will take sacks that could have been avoided by stepping up.

Summary: No one would mistake Clemens for a prospect anymore. But has he positioned himself for a Josh McCown consolation prize as a premium backup? Clemens operates an extremely scaled-down system for the Rams, with tons of running plays, screens and easy rollout passes. It's never a good sign when your 30-year old journeyman is running the buggy-bumper rookie playbook. Rams victories under Clemens were spurred by a handful of big plays, plus defense -- Clemens was in strict "game manager" mode. A good assistant-to-the-manager backup needs to complete short passes consistently, and Clemens' lack of touch and accuracy cause real problems in this area.

Decision: KO. A team with playoff aspirations needs a more capable backup than Clemens.

Matt Flynn, Packers

Who is He? A one-game wonder who actually had two productive games as Aaron Rodgers' backup, Flynn earned the highest headline-to-pass-attempt ratio of any currently-employed NFL quarterback in 2012 and 2013 by losing gift-wrapped starting opportunities in Seattle and Oakland, then bouncing from Oakland to Buffalo to Green Bay as the quarterbacking equivalent of a set of spare jumper cables.

What He Does Right: Still possesses some short-range accuracy and read-step-throw capability in a spread offense. Looked comfortable running hurry-up drills for the Packers against the Vikings.

What He Does Wrong: The longer a play develops, the worse Flynn gets. Looks like a man without a plan once his first read is exhausted. Takes too many sacks in the pocket, but is a terrible passer on the move who often just bails and throws out of bounds. Deep passes are usually short and off-target; his best tactic is to hope for defensive contact. Accuracy deteriorates after a few hits. Flunks the SATS test: low scores for arm and athleticism, and his sojourn around the league that proves how eager coaches are to try someone else.

Summary: Many of us were fooled into Flynn was an off-brand Drew Brees after his 2010 and 2011 spot starts for the Packers. He is really an off-brand Kevin Kolb: too sack-prone, too likely to roll to his right and surrender. But Flynn lacks Kolb's arm and ability to earn the faith of his bosses. It is hard to see what he offers that a team cannot get from a practice squad quarterback with a big body, arms and ambition, if little else.

Decision: KO. We have seen enough.