Not all to-be rookies have their day at any point during a NFL Draft. Clubs bring undrafted rookies into training camps every spring and summer, hoping to find squad players who may, at some point down the road, be able to contribute on Sundays.
Every now and again, a team hits on an undrafted player who was either underrated by draft scouts or who wasn't part of a draft class for whatever reasons. In some cases, the best of those players prove why it's said that the NFL Draft is very much an inexact science.
Here are the top 10 undrafted free agents who made it to Canton. They are ranked in chronological order.
15 Frank “Gunner” Gatski -- C -- Cleveland Browns
Gatski earned himself a tryout with the Browns in 1946. Needless to say, it worked out rather well. A player who featured on the offensive line and at linebacker early into his pro career, Gatski eventually settled in as the club's starting center.
He would prove to be a mainstay of multiple championship o-lines.
Gatski earned himself first- and second-team All-NFL honors every year from 1951 through 1955. He was a first-team All-Pro on three occasions. An incredibly durable player, Gatski never missed a game or even a practice during his professional career.
Gatski was enshrined in Canton in 1985.
14 Lou “The Toe” Groza -- K/T -- Cleveland Browns
They don't make football players like Groza anymore. A left tackle who just happened to be a solid placekicker, Groza made all but one Pro Bowl squad in the 1950s. He led the AAFC in points scored in his first season in that league (84), and Groza led the NFL in points in 1957 (77).
The 1954 Sporting News' NFL Player of the Year, Groza currently sits at 15 all-time in points scored (1,608).
Perhaps the greatest single moment of his career came in 1950. With the Browns trailing the St. Louis Rams 28-27 in the final seconds of the NFL Championship Game, Groza lined up for a 16-yard field goal. Groza put the kick right down the middle, winning the contest and the title for Cleveland.
13 Marion Motley -- FB -- Cleveland Browns
Motley, one of the first to break through pro football's race barrier, was one of the best all-around football players of his time. He possessed tremendous agility and quickness for his size (6-foot-1 and 232 pounds). He had the goods to excel on both sides of the football. Motley created holes in Cleveland's rushing and passing games, and he himself was a great rusher.
His 5.7 yards per carry average is good for sixth-best all-time.
Motley was named to first- and second-team All-AAFC and All-NFL teams for five straight years (1946-1950). Lingering knee injuries and other problems that come from playing such a brutal style ended his career after 1955. Motley was inducted into the Hall of Fame in 1968.
12 Bill Willis -- MG -- Cleveland Browns
Willis was, like Motley, one of the first African Americans to play in modern pro football. At 6-foot-2 and 213 pounds, Willis was thought to be too small to be a star on the offensive and defensive fronts. What wasn't accounted for was that Willis was one of the quickest linemen of his era.
A modern linebacker decades before his time, Willis was a first-team All-Pro from 1951-1953. He was named to the Pro Football Hall of Fame All-1940s Team. His touchdown-saving tackle in a 1950 playoff game versus the New York Giants preserved Cleveland's pursuit of a NFL title.
His day in Canton came in 1977.
11 Joe “The Jet” Perry -- FB -- San Francisco 49ers
Jim Brown is the greatest running back of all time, and one of the best football players to ever lace up a pair of boots. Before Brown was Joe Perry.
Perry appeared in 181 contests over 16 pro football seasons. He led the AAFC in rushing yards in 1949 (783). Perry led the NFL in rushing yards in consecutive seasons in 1953-54, when he was the first player in league history to rush for over 1,000 yards in back-to-back campaigns.
Perry retired as the NFL's all-time rushing leader with 9,732 yards, a mark that was later broken by the previously mentioned Brown. The 1954 NFL UPI MVP, Perry is in both the Pro Football Hall of Fame and the Pro Football Reference All-1950s Teams.
10 Emlen Tunnell -- DB -- New York Giants
Tunnell, the first African American to ever play for the Giants, was also the first African American to be elected into the Pro Football Hall of Fame. Tunnell was a solid returner and special teams player. He led the NFL in punt return yards in 1951 and 1952.
It was what Tunnell did while in the secondary of what was known as New York's “Umbrella Defense,” however, that landed him in the Hall of Fame.
Tunnell, in 14 pro football seasons, never went a single season without at least one interception. His career highest for a season was ten picks in 1949. Only one player, Paul Krause, had more career interceptions (81) than Tunnell (79).
9 Jack Butler -- CB -- Pittsburgh Steelers
Butler was one of the more underrated cornerbacks in football early on in his career. He had 25 interceptions and four pick-sixes in his first four seasons, and yet he wasn't named to the Pro Bowl a single time. He didn't have an interception in the 1955 season, but he made it to the Pro Bowl that year.
Butler would pick off 27 passes from 1956 through 1959. A severe injury that he suffered during a game in '59 ended his career after that season, but he had already built himself quite the impressive Hall-of-Fame resume. Following his playing days, Butler revolutionized the way younger players are scouted.
8 Dick “Night Train” Lane -- DB -- Los Angeles Rams
Lane just wanted a job when he ventured out to Rams training camp in 1952. The LA coaching staff placed Lane in the team's secondary, where he made quite the impact right out of the gate. Lane picked off 14 passes in his debut season.
That, to this day, remains the record for most interceptions from any one player in a season.
Lane had only three interceptions in 1953, and he was then traded to the Chicago Cardinals. He immediately awarded his new team with a 10-pick campaign. He had 30 interceptions in six seasons with the Cardinals before he moved on to the Detroit Lions.
Lane, a three-time first-team All-Pro, is fourth all-time in career interceptions with 68. He was named to seven Pro Bowl squads, and he is a member of the Pro Football Hall of Fame All-1950s Team.
7 Willie Wood -- DB -- Green Bay Packers
Wood was part of the first ever NFL dynasty of the Super Bowl era. After appearing in 12 contests in his first season in the league, Wood became a starter for the Packers. He would then go on to play in every one of Green Bay's games from 1961 until he retired following the 1971 season.
Wood had 48 picks in his 11 seasons as a starter. He was named to eight Pro Bowls from 1962 through 1970. Wood was also an accomplished punt returner. He took two punts for touchdowns in 1961, during which his 16.1 yards per return average was the best in the league.
Wood was inducted into the Hall of Fame in 1989.
6 Willie Brown -- DB -- Houston Oilers
Houston picked up Brown's rights after the draft before ultimately cutting the cornerback. Brown then moved on to the Denver Broncos, where he began to show in his second season in the NFL that the Oilers had made a mistake.
Brown played 16 seasons in the NFL, and he never went a season without grabbing at least one interception. He took a pick-six 75 yards to the house in Super Bowl XI, a touchdown that put that contest out of reach. Brown's 75-yard interception return was, at the time, a Super Bowl record.
Brown made nine Pro Bowl squads throughout his career, and he was a five-time first-team All-Pro. He was named to all-league teams seven times.
5 Emmitt Thomas -- DB -- Kansas City Chiefs
Thomas had somewhat of a slow start to his pro career. He started in only three games in 1966, and he didn't notch a single interception in his rookie year.
From there, Thomas grabbed 58 interceptions in the next 12 seasons. He led the AFL in interceptions in 1969 with 9. Five years later, Thomas had a NFL-best 12 picks. Only four players in history have finished with more interceptions in a season than what Thomas had in 1974.
Thomas possesses KC's all-time interception record. He is currently the secondary coach for the Chiefs.
4 Larry Little -- G -- San Diego Chargers
Little made four starts, and he appeared in 24 contests in his first two seasons with the Chargers. San Diego then traded him to the Miami Dolphins in 1969, and Little responded by having his first ever Pro-Bowl season.
Little eventually became a mainstay for Miami at right guard. He evolved into a vaunted pass blocker who also had the athleticism necessary to be a lead blocker on sweeps. While he didn't make headlines, Little was a key part to the rushing attack of the perfect '72 Dolphins.
Little was a first-team All-Pro every year from 1971-75. He was inducted into the Hall of Fame in 1993.
3 Jim Langer -- C -- Cleveland Browns
The Browns have, in the team's history, found several gems outside of draft classes. The team gave Langer a shot in 1970, but he didn't make it out of Cleveland's training camp. Langer landed with the Miami Dolphins, where, after two seasons, he became the team's starting center.
He started every game at the position for Miami from 1972 through 1979. Of all of the talented linemen on that perfect Dolphins side, Langer is often viewed as having been the best. The two-time Super Bowl Champion was a first-team All-Pro four times in his career.
2 Warren Moon -- QB -- Houston Oilers
After he achieved much success as a quarterback in the Canadian Football League, the Oilers gave Moon a shot in 1984. It was a decision that the franchise would not regret. Moon, the key man in Houston's “run and shoot” offense, led the NFL in completed passes and in passing yards in 1990 and 1991. He also led the NFL in passing TDs in 1990, a year in which the AP named Moon the Offensive Player of the Year.
After going 10-4 in 1993, Houston traded Moon to the Minnesota Vikings. Moon then passed for over 4,200 yards in his first two seasons with the Vikes. He sits sixth all-time in passing yards with 49,325.
Moon is also second all-time in career fumbles with 161.
1 John Randle -- DT -- Minnesota Vikings
In Randle, the best for this list may have been saved for last. He didn't light anybody on fire in his first season, accumulating one sack and one forced-fumble. He followed that up by picking up 9.5 sacks in 1991.
Following that, Randle would have no fewer than ten sacks per season every year from 1992 through 1999. In his final four seasons in the NFL, Randle had 31.5 sacks. His 137.5 career sacks is good for seventh-best in NFL history.
Randle was a first-team All-Pro every season from 1993-98. The Pro Football Hall of Fame and Pro Football Reference list him on their All-1990s first teams. After he was a finalist in 2009, Randle was inducted into the Hall of Fame in 2010.