Former Redskins and Texans general manager/NFL analyst Charley Casserly conducted a 10-year study that concluded round-by-round percentages of draft picks developing into “Successful” players. The study was done through the use of his personal scouting reports, analyzing others, watching game-tape, and “Numerous interviews with coaches and personnel people in the NFL.” Casserly defined “Successful, as a player developing into a starter within four years of being drafted.”
Casserly found that First-round draft picks have a 75% chance of success. Second-rounders, 50%. Third-rounders, 30%. Fourth-rounders, 25%. Fifth-rounders, 20%. Sixth-rounders, 9% and Seventh-rounders, 5%.