The purpose of the NFL Draft is to control talent.
If it was open season for teams and rookies, the most competitive and well-off franchises would attract all the best talent.
After seven rounds of the worst teams getting "dibs" on their favorite prospects and the best teams going last, parity is fostered, and the league stays balanced.
Somewhere around the sixth round, though, teams start targeting priority free agents. Calls are discreetly made between teams, agents and players to begin working on deals if the players fall through the end of the seventh round.
As LouisianaDaily.com reported, former LSU wideout Russell Shepard admitted to radio station WNXX that he "signed" with the Eagles while picks were still coming off the board. Why commit this huge no-no?
As Mike Florio of Pro Football Talk explained, Shepard believes he'll have the opportunity to contribute in several different ways in Philadelphia. Why wouldn't he go to a team who's enthusiastic to have him instead of a team who's just crossing the next name off its list?
Putting aside the "because it's against the rules" thing, this is exactly why undrafted free agents are so important: They may not have been one of the consensus best 250-or-so players, but when they get put on the team where they fit best, they can make a big impact.
Here are 20 of the most notable undrafted free agents, where they went, my grade of just how good of a fit their teams are and how likely they are to make an impact.
Alvin Bailey, a 6'3", 312-pound guard from Arkansas, declared himself eligible for the NFL draft despite the Razorbacks leaving plenty of business unfinished in 2012.
Bailey's 5.25 40-yard dash time betrays his lack of second-level speed, but he's got excellent strength and suddenness, and his technique is still improving.
Bailey still has plenty of upside left to hit, but he seems a poor fit for the Seahawks' zone-based blocking scheme. Even if he develops his body and technique, it's hard to see Bailey becoming a quality starter for Seattle.
Brad Wing, an Australian punter, drew a lot of attention at LSU for his huge punts in crucial moments of big games.
As an experienced rugby punter with a big leg, Wing would fit in with almost any NFL club. But the Eagles were already looking to upgrade their punting from 2012.
Earlier in the offseason, the Eagles released Mat McBriar and signed Donnie Jones. Could Wing unseat Jones?
Braxston Cave, a 6'3", 303-pound fifth-year senior center from Notre Dame, has all the leadership qualities teams look for in the "quarterback" of the offensive line.
He doesn't have exceptional size—which can be desirable for centers on teams with quick-timing offenses.
Cave, however, doesn't display the great second-level athleticism smaller centers usually do. That said, Cave's durability and track record at Notre Dame certainly qualified him as a draftable prospect. The Browns, who lack a true backup for center Alex Mack, may have gotten a great bargain.
When discussing undrafted free agents, the word "snubbed" rarely comes up. "Slider" or "faller" will get tossed around for an obviously gifted prospect who doesn't get picked in seven rounds.
This makes it seem like it's a quality of the player himself: Chase Thomas is a "slider" or a "faller."
Thomas, though, didn't slide or fall: He got snubbed.
His 6'3", 244-pound frame is big enough. His 4.91 40-yard dash wasn't blazing fast but wasn't painfully slow. All of his other combine measurables were excellent: 32" vertical jump, 113" broad jump, 7.17 three-cone drill and 4.31 short shuttle.
Regardless, Thomas went to a New Orleans Saints team trying to put teeth back into their 3-4 defense. He should not only make the roster with ease, he could make an impact sooner rather than later.
NFL.com's Gil Brandt—arguably the father of modern football scouting—rated Cory Grissom the best undrafted defensive tackle.
When an evaluator like Brandt puts his stamp of approval on a prospect, that means something.
Grissom, a 6'1", 306-pound run-stuffer with a low, wide frame, is a perfect fit for a New England Patriots team who likes to flex between 3-4 and 4-3 base alignments. Grissom has struggled to stay healthy, but he's the kind of chess piece Bill Belichick can find uses for.
One of three former Tennessee wide receivers in the 2013 draft class with eye-popping measurables, stats and tape, Da'Rick Rogers went undrafted partially because he didn't finish his college career at Tennessee.
After struggling with drug problems, Rogers had to transfer and play his last season of eligibility at Tennessee Tech.
If Rogers can recover the form that made him a standout at Tennessee, the playmaker-hungry Bills certainly have a spot for him. Only time will tell if he can stay clean and hungry, though.
Sam Houston State's Daxton Swanson stands 5'10" and weighs 186 pounds. At the combine, he ran a 4.56 40-yard dash, lifted 225 pounds 15 times, leapt 33" in the air and broad jumped 10'2".
Those numbers are NFL caliber, but they aren't outstanding. Swanson's 14 interceptions in three seasons as a contributor, though, certainly catch the eye. In fact, his junior season, Swanson set a school record with eight picks.
The Colts, even after trading for Vontae Davis last season and signing Greg Toler in the offseason, still need help at cornerback. If Swanson can learn how to apply his knack for the ball in the big leagues, he'll be a valuable addition.
At 5'6", 196 pounds, Dennis Johnson is a wrecking ball of a running back. His low squat frame, moves and kick-return ability will remind many football fans of Jacksonville Jaguars running back Maurice Jones-Drew.
The one trait Johnson lacked in comparison to college teammate Knile Davis was outstanding deep speed—yet, with pro day 40-yard dash times of 4.47 and 4.49, he's no slowpoke.
The Texans don't seem to be in desperate need of a running back or kick returner, but Johnson is an NFL-caliber back.
Jakar Hamilton, at 5'11", 186 pounds, has good size for a cornerback. With a pro day 40-yard dash time of 4.56, he has good speed for a safety. His vertical leap (40.5") and three-cone drill time (6.93) are good for any position.
Hamilton, who can play either cornerback or safety, will likely play safety for the Cowboys, who are stacked with pricey corners.
Hamilton attended Georgia before transferring to South Carolina State and recently went on Dallas radio to discuss how much he'd love the Cowboys to draft him—if the Cowboys didn't draft Kenny Vaccaro.
Though Hamilton fell through the draft, it looks like the his admiration for the Cowboys was mutual.
At the college level, Jake Stoneburner was a very good two-way tight end with a great combination of size (6'4", 252 pounds), speed (low 4.5s at his pro day) and hands.
At the NFL level, Stoneburner's built more like a big wide receiver than a tight end; he likely won't be able to block inline with any kind of effectiveness.
Unlike other "Joker" tight ends, though, Stoneburner isn't a particularly fluid athlete, so he has trouble using his size/speed combination to dominate.
That said, the potential is there for him to excel with some good coaching and a good quarterback. Fortunately the Packers have both—and a need for receiving tight end depth.
Fauria, the nephew of retired 13-year NFL veteran Christian Fauria, stands an impressive 6'7" but weighs just 259 pounds. His lean, athletic frame and big, 10 7/8" paws make him a big target perfect for short-yardage situations. He had 12 touchdowns his senior season, as UCLA exploited his size.
Fauria doesn't have the bulk or leverage to block inline effectively, and he's not a speed demon, so he isn't a downfield threat. He's definitely got some useful tools in his bag, though.
Starters Tony Scheffler and Brandon Pettigrew both disappointed in 2012, so the door is open for Fauria to make an impact.
Like fellow linebacker Chase Thomas, it's hard to figure out why Kevin Reddick was available for the New Orleans Saints to pick up as an undrafted free agent. Reddick is a leader, was team captain and was first-team All-ACC inside linebacker his senior year.
Standing 6'1" and weighing 243 pounds, he's got enough size to lower the boom between the tackles and enough quickness that he was used off the edge as a pass-rusher and playmaker.
With the Saints, Reddick would be a perfect fit as a between-the-tackles run-stuffer in their 3-4 defense. They just so happen to have need for that.
There's an old idea among NFL talent evaluators—the "World Theory." It says that there are only so many true two-gap nose tackles in the world like 6'5", 342-pound Kwame Geathers.
Geathers didn't quite live up to his incredible potential at Georgia: He declared himself eligible for the draft rather than return for his senior season, which would likely have been his first as a full-time starter.
Without having shown the consistency teams value in an elite nose tackle, Geathers fell. But a player with his size and talent falling all the way through the draft is stunning. If the Chargers can motivate Geathers to excel, they'll have pulled one over on the rest of the league.
Mark Harrison has the kind of measurables that usually keep a prospect from falling out of the draft. At 6'3", 231 pounds with huge 35" arms, Harrison not only has sufficient size to make it in the NFL, he's got exceptional size.
With a 4.46 40-yard dash, 38.5" vertical leap and 129" broad jump, he's got freaky explosion.
Of course, if there weren't a downside, he wouldn't be available. Harrison is not a natural ball-catcher and doesn't use his gifts to attack his routes.
Finally, there's the matter of Combine Hotel Room Gate: Harrison and receiver DeAndre Hopkins were accused of nastily trashing their mutual combine hotel room, according to ESPN.com.
Still, Harrison's talent is worth more than a tire-kick, and the perennially receiver-starved Bears could easily find a place for him.
Matt Scott was a hot name in the second and third days of the NFL draft. What you might call a "late riser," media evaluators began to fall in love with Scott's potential and fit with several NFL teams.
As Sports Illustrated's Richard Deitsch wrote, ESPN's coverage even pegged Scott to be taken by the Philadelphia Eagles in the fourth round, when the Eagles drafted Matt Barkley instead.
Yet Scott wasn't drafted at all, and the Jacksonville Jaguars—ready to develop another quarterback behind Blaine Gabbert but not yet ready to announce they've given up on Gabbert—are a perfect fit.
It's not often an SEC running back with 4.42 speed and a 39.5" vertical leap is available as an undrafted free agent, but the Bears were lucky enough to snag 5'10", 210-pound Michael Ford anyway.
Ford struggled for playing time in LSU's stocked backfield, but he led the team in rushing in 2011. He certainly has NFL talent and could work his way onto an older-than-you-realize Bears tailback corps.
Miguel Maysonet, at 5'9", 209 pounds, has a great NFL build. His low center of gravity and excellent strength—he bench pressed 225 pounds 21 times at his pro day, per NFLDraftScout.com—make him hard to bring down.
Maysonet has exceptional durability despite an aggressive running style, and he goes hard and isn't afraid to take on defenders at the second level.
Maysonet isn't a jitterbug or a home-run hitter, but in the Eagles' zone-read offense, he should have no problem getting to the next level and making linebackers pay.
As Jason Kersey of The Oklahoman put it, the fall of Oklahoma Sooners safety Tony Jefferson was the most shocking Sooner-related storyline of the NFL draft—and there were a few of them.
Jefferson was one of the most touted defensive back recruits in the nation coming out of high school, and the 5'11", 212-pounder started nine games as a true freshman. Until he ran slowly at the NFL Combine, Kersey wrote, Jefferson was still considered a strong prospect in a relatively weak safety class—a likely mid-rounder.
When Jefferson fell out of the draft, legendary NFL.com draft guru Gil Brandt didn't include Jefferson in his list of top 10 undrafted free agent defensive backs.
Yet the Cardinals came calling, and after losing both Adrian Wilson and Kerry Rhodes, they have room on the depth chart.
When I watch tape of former Tennessee quarterback Tyler Bray, I don't see a player with the footwork, mechanics, vision or instincts to succeed at the NFL level. When NFL teams see his 6'6" frame and impressive arm, though, they see potential.
Instead Bray—tabbed as a mid-round pick by many and a likely target of the New York Jets by others—fell through the draft.
Lucky for him.
Bray instead goes to the Kansas City Chiefs, where he will definitely be stuck behind starter Alex Smith for at least the next two seasons. He'll also have the benefit of being coached by Andy Reid, one of the best offensive minds and quarterback-groomers in football.
It figured that the run-on offensive tackles had to end eventually, right?
The first two days and three rounds of the NFL draft saw offensive linemen with big frames snagged early and often. It wasn't until late in the third day that teams got their fill.
When the draft music stopped, poor 6'6", 321-pound Xavier Nelson seemed to be the last big-bodied lineman without a musical chair. His big frame, long arms and track record against SEC competition should have been enough to find a place.
His struggles with consistency earned him multiple benchings and left-tackle-to-right-tackle flip-flops, though, and NFL teams had all taken safer options earlier in the draft.
The Redskins, though, didn't snag an offensive tackle with any of their seven draft picks. They did sign tackle Jeremy Trueblood as a free agent to compete for a starting job. Nixon could easily find a spot on the roster if he proves he's got it figured out.