The NFL is a league of constant change â€“ one where we see coaches fired after just one season, and players cut without actually getting a significant chance. At times thatâ€™s bothered people. How can you possibly judge a coach or a player after such a short period of time?

This is especially true of quarterbacks. While fans (and franchises) will grow tired after a few years of poor or mediocre play (Christian Ponder), some will be forgiving after just one (Ryan Tannehill). Itâ€™s a point in which optimism becomes realism, something Iâ€™m sure Cincinnati fans are feeling at this very moment.

This feeling is a bit similar to what is described as â€œQB Purgatoryâ€ â€“ a place that feels like no manâ€™s land, where a quarterback is good enough to win some games, but not good enough to take a team to the next level.

And when a team is in fact in QB Purgatory, hope is that team's best friend. The franchise is optimistic that a player can all of a sudden come through and become a star. The team wants to believe they have the guy. After all, going for a brand new quarterback would be admitting defeat and starting over in today's NFL.

The fact is, however, we may be able to define how good or bad a player is going to be at the quarterback position after just one season of playing. Perhaps QB Purgatory doesnâ€™t have to exist. What if the quarterbacks who are winners and the ones who do become franchise passers are consistently performing at a high level during their rookie seasons? Conversely, what if quarterbacks who have poor rookie seasons historically never pan out?

I wanted to answer those questions and more. I wanted to see if a player like Mike Glennon, who struggled at times during his rookie season this past year, could ever become a top-notch passer based on how upper-tiered quarterbacks performed during their rookie campaigns. I wanted to dig into the numbers and see if a first-year quarterback with middling metrics and significant volume ever did something beneficial at the position after that initial season.

And for fans who are all about being patient, the results may change your mind.

Rookie Passing Data

Back in the day, drafting and starting a quarterback during his rookie season didnâ€™t happen a lot in the NFL. In fact, between 1986 and 1999 (14 seasons), only 23 quarterbacks saw 200 or more pass attempts during their rookie seasons. From 2000 to 2013, this number was 40.

In recent years, weâ€™ve seen rookie quarterbacks succeed: Russell Wilson, Robert Griffin III and Andrew Luck each took their teamâ€™s to the playoffs as first-year passers, and Ben Roethlisberger, back in 2004, went 13-0 in the regular season as a rookie starter.

The general thought was that those players, once their rookie seasons were over, would have obvious bright futures. Theyâ€™ve proven that theyâ€™re good quarterbacks at the NFL level. You donâ€™t go 13-0 (typically) and fall off the face of the Earth.

But as I mentioned in the intro, players who were adequate tend to move into their second seasons and beyond surrounded by optimism rather than realism. Buccaneers fans wonâ€™t be going into 2014 thinking, â€œAlright, weâ€™ve got our franchise quarterback" necessarily, but they could easily be thinking, â€œMan, I really hope Mike Glennon is our man.â€

If the numbers trend in a way that says otherwise, why have that optimism? Why not just move on?

Letâ€™s walk through the analysis. First, I gathered all 40 quarterbacks who saw 200 or more attempts during their rookie seasons since the year 2000. While this volume number is arbitrary, I thought it captured players who started at least 10 or so games as rookies.

The next step was to see how these quarterbacks performed. Fortunately, our Passing Net Expected Points (NEP) metric is the perfect tool for that, as it looks at how many points a quarterback added for his team during a given season through the air. To learn more about how it works, click here.

On average, the rookie quarterbacks who saw significant time since 2000 had a Passing NEP score of -28.24. The median of the data was -28.70. For some perspective, a number this low would have ranked in the bottom 10 among all passers in 2013. That generally makes sense, as rookie passers have no experience and, in turn, aren't as solid at the position.

Trends

The data below certainly doesnâ€™t tell the entire story about every quarterback to play the game since 2000. This is mostly because a lot of quarterbacks still donâ€™t start during their rookie campaigns. However, for the ones who do, the data provides insight as to whether or not they have bright, legitimate futures in the NFL.

To find some high-level trends, I divided the players up into four groups: Tier 1 (the top-10 quarterbacks in terms of Passing NEP), Tier 2 (quarterbacks 11-20), Tier 3 (quarterbacks 21-30) and Tier 4 (quarterbacks 31-40). Information on each tier is below:

Tier 4

Rookie Passing NEP Range: -64.39 to -128.24

Quarterback Passing NEP Passing NEP/Drop Back Mark Sanchez -68.36 -0.18 Geno Smith -68.55 -0.14 Bruce Gradkowski -69.59 -0.20 Jimmy Clausen -83.81 -0.25 Andrew Walter -86.20 -0.27 Blaine Gabbert -86.44 -0.19 Chad Hutchinson -89.52 -0.32 Kyle Orton -99.94 -0.25 Chris Weinke -105.24 -0.19 David Carr -128.24 -0.25

We could probably call this tier the â€œI have no business starting in the NFLâ€ tier, but I supposed â€œTier 4â€ works. Essentially, this oneâ€™s filled with failures, though, to be fair, not every quarterback in this tier was a top one coming out of school. The only player to win a playoff game out of this group was Mark Sanchez, and, well, we know that story.

The max Passing NEP in Tier 4 was scored by the aforementioned Sanchez, coming in at -68.36. Funny enough, replacement Geno Smith is there right behind him. Either Rex Ryan is horrible at managing quarterbacks, or the Jets are just that bad at picking them through the draft. Iâ€™ll go with both.

This isn't good news for a guy like Smith though. It looks as though, essentially, if a rookie quarterback hits this -68.00 Passing NEP, you canâ€™t really expect much in terms of a future. Though someone like Bruce Gradkowski wasnâ€™t exactly highly touted out of school, half of these players were drafted in the first or second round of the NFL Draft. In other words, these guys werenâ€™t just bums who stayed bums.

Tier 3

Rookie Passing NEP Range: -28.36 to -55.54

Quarterback Passing NEP Passing NEP/Drop Back Sam Bradford -29.04 -0.05 Carson Palmer -30.12 -0.07 Christian Ponder -33.49 -0.10 Kyle Boller -33.52 -0.14 Josh Freeman -39.56 -0.13 Vince Young -47.29 -0.12 E.J. Manuel -47.84 -0.14 Ken Dorsey -54.47 -0.23 Matthew Stafford -55.54 -0.14 Joey Harrington -64.39 -0.15

The passers are getting a little better now, but they're still pretty bad. Of the 10 quarterbacks in Tier 3, four have led their teams to the playoffs, but in total, the players have zero postseason wins. And of these quarterbacks, only Matthew Stafford, Carson Palmer (Note: Palmer was not a rookie when he first played, but didn't play a single snap during his rookie campaign, which is how he hit this list) and Josh Freeman have been able to crack the 20.00 Passing NEP mark in a single season, a number that nowadays is very average in the league.

The only real player in this group that might be or become a legitimate top-tier quarterback is Matthew Stafford. He has plenty of his own flaws, however, and is overly reliant on his top receiver, Calvin Johnson. He also has a tendency to turn the ball over, and his 13-to-20 touchdown-to-interception ratio season in 2009 is a key reason he's placed on this list.

Carson Palmerâ€™s somewhat of a wildcard as well, but can we say with any confidence that heâ€™s ever going to take a team the distance? Heâ€™s been erratic throughout his career, and has already played 10 NFL seasons. Iâ€™ll pass on the notion that heâ€™s any sort of outlier within this tier.

Perhaps this doesnâ€™t bode well for E.J. Manuel, who sits as the third-worst rookie quarterback in the tier.

Tier 2

Rookie Passing NEP Range: 6.99 to -23.43

Quarterback Passing NEP Passing NEP/Drop Back Matt McGloin 6.66 0.03 Patrick Ramsey -3.34 -0.01 Colt McCoy -6.38 -0.03 Joe Flacco -7.53 -0.02 Byron Leftwich -13.27 -0.03 Nick Foles -13.38 -0.05 Brandon Weeden -19.66 -0.04 Ryan Tannehill -22.63 -0.04 Mike Glennon -23.43 -0.05 Trent Edwards -28.36 -0.10

Thereâ€™s a mixed bag in this chunk of quarterbacks, as we have players like Brandon Weeden who will probably amount to nothing, all the way to Joe Flacco who ended up winning a Super Bowl. However, none of these guys, aside from potentially Nick Foles, are true gunslingers - theyâ€™re mostly game managers who found success at times in the NFL. While Joe Flacco has seen winning success, his quarterback numbers have been average throughout his career.

It seems as though, given our fairly small sample, if a quarterback finishes in this group, things could go many different directions. So sorry, Bucs fans - there may no be definitive answer for Mike Glennon, aside from the fact that he'll probably never amount of being a true franchise quarterback.

Tier 1

Rookie Passing NEP Range: 12.64 to 89.16

Quarterback Passing NEP Passing NEP/Drop Back Matt Ryan 89.16 0.20 Russell Wilson 84.01 0.20 Robert Griffin III 73.63 0.17 Ben Roethlisberger 62.25 0.19 Cam Newton 57.48 0.10 Marc Bulger 44.51 0.20 Andrew Luck 36.68 0.05 Matt Leinart 18.26 0.05 Andy Dalton 12.64 0.02 Jason Campbell 6.99 0.03

No, itâ€™s not a surprise that, on this entire list, the only true franchise quarterbacks outside of maybe Joe Flacco and Nick Foles landed in Tier 1. Here weâ€™ve got Ben Roethlisberger, Cam Newton, Russell Wilson, Robert Griffin III, Andrew Luck and, to a lesser extent, Marc Bulger.

Though Bulger wasnâ€™t drafted by the Rams and moved around over his first two NFL years, he made this list because he was never active for any of the Rams games in 2001. In 2002, Bulger came in after an 0-5 start and went 6-0 in games that he actually started and finished.

If youâ€™ve forgotten, Bulger was a decent NFL quarterback through the years, but had trouble staying healthy. Franchise quarterback? No, but he certainly ended up better than a lot of the guys on this entire list.

Also, Bengals fans: Thereâ€™s some hope given Andy Daltonâ€™s sitting pretty at the nine spot, but perhaps that optimism is driven into the ground when you see that Matt Leinart is a spot ahead of him. I was just surprised as anyone to see Leinart make this list, trust me. But the numbers donâ€™t lie.

A general rule of thumb moving forward could be that, if a quarterback has a rookie campaign where he sees a Passing NEP of about 30 or above, that passer has a decent chance to do a whole lot of good in the NFL.

Key Takeaways

I'm fully aware that a study like this could go a lot deeper. Team weapons, coaching â€“ all of that goes into how well a quarterback performs over the course of his career as well. But at the same time, thatâ€™s the nature of the NFL. Quarterbacks often times can have poor careers because they werenâ€™t placed in the right situation from the start.

The fact of the matter is that there seems to be a clear connection between a quarterback performing at a moderately high level during his rookie season versus the quarterbackâ€™s future success, as long as that quarterback does, indeed, play his rookie season. Just move your eyes from top to bottom on that list, and youâ€™ll see just that.

This is by no means the end all to grading whether or not a signal-caller will succeed, but it certainly canâ€™t be ignored. For instance, Jets fans should be worried about Geno Smith. The fact that he had such a low Passing NEP total during his first season doesnâ€™t bode well considering how other players with that type of production did over the long run.

The same could almost be said for E.J. Manuel or Mike Glennon. Of course each situation is unique, but given history, quarterbacks whoâ€™ve performed the way they did during their rookie season typically have been nothing better than passers who make the playoffs, at most, every once in a while.

The bottom line is that excusing a rookie campaign and saying that a quarterback was â€œjust showing growing painsâ€ may not be valid. That is, unless you want mediocrity for a franchise.