The NFL is always evolving and establishing new trends. In recent times, the league has gone from being pass-happy to pass-saturated.
Since the 2009 season, only four teams have run the ball over 500 times in a season. Just a decade ago, twice as many teams ran the ball that much in a single season. While the running game still matters because both offenses and defenses need to be balanced, the passing game is evolving in different ways.
Instead of focusing on tight formations that drag defenders to the line of scrimmage and ask more than five players to win physical battles upfront, offenses today are trying to create space and matchups by spreading players around.
With that in mind, the big receiving tight end remains a prevalent player in most offenses.
This is epitomised by Jimmy Graham of the New Orleans Saints. Despite being just a raw athlete when he entered the league four seasons ago, he was a priority for many teams this offseason. He was expected to be the top available player in free agency, but New Orleans used the franchise tag on him before he could hit the market.
Graham is a star in the league now because he can tower over most defensive backs and run away from most linebackers.
Because of players such as Graham, Antonio Gates, Tony Gonzalez, Rob Gronkowski and others, NFL defenses are now evolving to adapt to these athletes on the offensive side of the ball. The Seattle Seahawks were the first team capable of consistently taking away matchup advantages with their own athletes on defense.
The reigning Super Bowl champions didn't have a defense that can be easily replicated. The talent strung through that roster from top to bottom was exceptional and came as a result of late-round draft picks who developed quickly. With so many star players on minimal contracts, the Seattle Seahawks could afford to pay more money to complementary pieces.
If you take the Saints as an example, you can see that they must work under more financial constraint. Unlike Russell Wilson and Richard Sherman, the team's two best players, Drew Brees and Jimmy Graham, are owed massive amounts of money.
While not being able to benefit from cheaper contracts, the Saints have created a defense that can adapt to NFL passing attacks by focusing on their secondary.
During the 2013 offseason, the Saints signed 6'1" cornerback Keenan Lewis in free agency. As a Pittsburgh Steelers starter the previous season, he led the league with 23 pass deflections. He was able to do that because he is a very long, rangy athlete.
Along with Lewis, the Saints acquired Kenny Vaccaro in the first round of the NFL draft. The Vaccaro selection was expected because the Saints desperately needed secondary help, but the type of safety that he was suggests it wasn't simply a desperation pick.
Lewis is a tall cornerback who can run; therefore, he is capable of covering players such as Alshon Jeffery, Anquan Boldin and Julio Jones. Those big, physical receivers that essentially post up cornerbacks to rebound passes that are thrown their way don't get simple catches against a player like Lewis.
Being able to match up to big receivers is important nowadays, but an inability to cover smaller receivers negates that.
Lewis struggles when asked to move inside and cover receivers who rely on lateral quickness, but he is quick enough to be effective against those kinds of receivers on the outside. This is where Vaccaro comes into play.
Vaccaro is an exceptionally versatile safety who can play in the box, cover deep and line up in press coverage over slot receivers.
His versatility and athleticism made him a very impressive individual player last season, but his overall impact on the team was lessened by the caliber of players around him. Roman Harper and Malcolm Jenkins were the Saints' other two safeties. Harper is a typical strong safety, while Jenkins is a typical free safety.
Neither player was exceptionally effective at what they were best suited to do, but even if Jenkins was great in coverage and Harper was great in the box, they wouldn't have had the versatility to be effective starters.
Jenkins lacks physicality and is a horrible tackler. Harper is too slow to run with tight ends or turn and cover receivers. Both players could be targeted by the offense in specific ways.
With that in mind, both players were let go by the Saints this offseason. Harper was released, and Jenkins joined the Philadelphia Eagles as a free agent. Harper's replacement, Rafael Bush, was retained as a restricted free agent, while Jairus Byrd signed as a priority free agent to replace Jenkins.
Even though Bush and Byrd are clearly better in specific roles, both are well-rounded players who won't be exposed by different assignments.
The safety position in recent times has blurred. Despite the success of Kam Chancellor and Earl Thomas, two players who are widely recognized as a combination of a strong and a free safety, the league is moving away from those labels at the position.
Safeties who only fit specific roles are no longer desirable. Byrd was a top free-agent safety not only because he excels in a free safety role, but also because he can be an effective closer to the line of scrimmage. Those are the types of safeties who are expected to go in the early part of the first round of this year's draft.
Ha'Sean Clinton-Dix, Calvin Pryor and Jimmie Ward all have their respective flaws, but each also has the potential to be an all-around starter in the pros.
Finding superstar talents who can be versatile safeties and big cornerbacks isn't easy, but not being able to find the same quality doesn't mean you can't find the same style. In New Orleans, the Saints don't have a secondary that can compete with Seattle's as the best in the league, but their unit could help them become one of the very best defenses as a whole in the NFL next season.
The Seahawks won the Super Bowl in convincing fashion last season because they had a dominant defense. A strong secondary was a huge part of that, but they have also adapted in other specific ways that put them ahead of the curve.
Malcolm Smith, the Super Bowl XLVIII MVP, is a weak-side linebacker with impressive athleticism. K.J. Wright, the Seahawks' starting weak-side linebacker, also plays the game with impressive athleticism.
When Wright was injured late in the 2013 season, Smith stepped into his starting role. When Wright returned for the NFC Championship Game, he barely played because he wasn't 100 percent healthy. He was healthy for the Super Bowl, but he didn't take Smith's spot.
Smith and Wright combined for 86 snaps, per Pro Football Focus (subscription required) in the Super Bowl. The Seahawks' strong-side linebacker, Bruce Irvin, played just 19 snaps, a number that was bloated by snaps at defensive end.
The days of every 4-3 base defense carrying a strong-side linebacker may be over.
Strong-side linebackers are typically bigger than weak-side linebackers. They play to the tight end's side of the field and excel at stopping the run. James Harrison playing with the Cincinnati Bengals last season was an example of a strong-side linebacker.
The problem with a player like Harrison is that he can be taken advantage of in space. Instead of having someone like him on the field, teams are more likely looking to find players who are comfortable in coverage and passable against the run.
This is reflected by the consensus top two non-pass-rushing linebackers in this year's draft. Neither C.J. Mosley nor Ryan Shazier are big-bodied players. Both are coverage linebackers with the strength and quickness to work around blockers in traffic against the run.
Whether they become weak-side linebackers in 4-3 defenses or inside linebackers in 3-4 defenses, each player has the versatility to counter the NFL's passing offenses.
The final trend building on the defensive side of the ball in the NFL comes on the defensive line. Michael Bennett shot to prominence with the Seahawks because of his ability to rush the passer. Three of his sacks came when he lined up inside last season, while he was able to consistently create pressure from all over the line of scrimmage.
Players such as Bennett, J.J. Watt, Calais Campbell, Geno Atkins, Jurrell Casey, Muhammed Wilkerson and Kyle Williams are now more of a priority than edge-rushers.
Campbell entered the NFL in 2008 as predominantly an edge-rusher. In the six seasons since, he's spent time all along the Arizona Cardinals defensive line. As quoted by Robert Mays of Grantland.com, it was a transition to which Campbell had to adapt on the fly.
"I’d never played inside before. I’d never played a three technique or five technique. It was a whole new position for me. The first year, it was just about learning."
Most NFL quarterbacks are now able to adjust to edge pressure consistently. Very few can handle interior pressure on a regular basis. It is more likely to push a quarterback off his spot and disrupt his line of vision than edge pressure.
Because of the success of players such as Campbell, Watt and Atkins in particular, interior pass-rushing prospects such as Aaron Donald, Ra'Shede Hageman, Will Sutton and Dominique Easley are expected to go higher in the draft.
The more this league changes, the more important the quarterback position becomes.
It's not tough to recognize the changes in how the quarterback position has been viewed over the last decade or so. Accepting players such as Cam Newton, Colin Kaepernick, Russell Wilson and now Johnny Manziel as two-way threats instead of trying to force them to become pocket passers is now the norm.
Manziel is the fork in the road. He is not as big as Newton or Kaepernick, so it's unlikely that he can run as often as those two players do. For all of Wilson's athletic ability, he is exceptionally intelligent and very comfortable in the pocket. Manziel's play in college suggests that he may never turn into what Wilson is now.
In previous years, Manziel would have been the type of player who would be considering a position change or hoping to be a late-round developmental pick by someone.
While he may not go in the top five or the top 10, Manziel is not expected to fall into the second round, and it seems almost impossible to think he might fall into the third round. Even though there is talk of Tom Savage climbing boards based on his size and arm strength, acceptance of different types of quarterbacks is becoming more widespread.
Manziel is a fork in the road because, if he fails, Wilson will be pointed to as this generation's rare exception for short quarterbacks. If he succeeds, the acceptance of smaller players at that position will continue to grow.
The way NFL teams evaluate big-armed, big-bodied passers will not be the same for the next decade or so at least.
Of course, attempting to account for anything that happens in the NFL over the next decade is dangerous territory. Whether it's the rules, the philosophies or the schemes, things will continue to change as the NFL continues to evolve.