There aren't many players in the 100 years of the National Football League who have been responsible for changing the game. On that super-short list is Bob Hayes, the gold medal Olympic sprinter who forced defensive coordinators to come up with new ways to combat his speed.

Trying to defend Hayes led to zone defenses as well as dropping the second safety deeper downfield, especially in passing situations, both of which are still employed today.

"I know one thing, and I played with him," teammate and fellow Hall of Famer Mike Ditka said. "He changed the game. He made defenses and defensive coordinators work hard to figure out what you had to do to stop him."

While Hayes attended Florida A&M on a football scholarship and became one of the first African-Americans to appear in the Senior Bowl, he was not truly considered a football player. He was a world-class sprinter who never lost a race in college and won two gold medals in the 1964 Summer Games in Tokyo, tying a world record in the 100-meter dash and helping set a new mark in the 4x100 meter relay. That same year, the Cowboys selected him in the seventh round of the draft.

Make no mistake, Hayes was a work in progress, former teammate Walt Garrison saying of the wideout, "He couldn't catch a cold in a blizzard." Still, the speed was just so game-changing, and he was usually so wide open that Hayes still cracked 1,000 receiving yards as a rookie in 1965 and led the league with 12 touchdowns. The following season was the best of his career: 64 catches, 1,232 yards and a league-best 13 scores.

"You know what's scary?" Hall of Famer and teammate Mel Renfro said. "I always felt Bob never ran as fast as he could. He just ran as fast as he needed to."

Hayes was a Pro Bowler in each of his first three seasons and an All-Pro selection in 1966 and 1968. There were so many long touchdown runs – 82 yards, 85 yards, 89 yards, 95 yards – because there was just no one who could catch him from behind. He also was equally dangerous on punt returns, returning three for scores in two seasons (1967-68).

The only two players in NFL history with at least 300 career receptions to average 20 yards per catch are Paul Warfield and Hayes, both of whom are members of the Pro Football Hall of Fame. "Bullet Bob" was also inducted into the Ring of Honor in 2001.

His final career numbers of 7,414 receiving yards and 71 touchdown catches, which was a team record until 2017, are impressive on their own, but fail to remotely explain the impact Hayes had on the game. That, and being the only man to ever win a gold medal and a Super Bowl, is quite the legacy.