The junior announced on Sunday that he would be foregoing his senior season and turning pro after the Broncos' final game of the year against Arizona in the Fiesta Bowl.
"This is my dream," Ajayi said at a press conference. "I'm chasing it ... Having the opportunity to chase this dream is the best feeling in the world."
The tailback was a big reason why the team won the Mountain West title this season and earned the Group of Five bid to a New Year's Six bowl game. The 6-foot, 215-pounder is second in the nation in yards from scrimmage and is tied with Wisconsin running back Melvin Gordon for first with 29 total touchdowns.
"There's nothing Jay can do a year from now that's going to make his draft grade any higher," Boise State running backs coach Kent Riddle added. "We knew he's going to get a decent draft grade when all that comes back. It really did seem like the only right answer to give him was to (go)."
Ajayi noted the limited number of carries that running backs have in them and the possibility of injuries, such as the one Georgia's Todd Gurley suffered, contributed to him making the jump to the NFL.
Known as a workhorse, Ajayi has started to build considerable buzz in scouting circles with a strong finish to the 2014 season.
"The "J-Train" has been a monster running between the tackles for the Broncos, exhibiting outstanding vision, pitter-pat and toughness," NFL Media analyst Bucky Brooks noted. "With Ajayi also displaying home-run speed and acceleration, scouts should pay close attention to the burgeoning superstar who is running rampant in the Mountain West."