The veteran coach walked away from a once in a generation superstar in Tebow into a meeting room where former unrecruited walk-on Tyson Lee was the heir apparent at quarterback.
A fall media relations release revealed a five man depth chart at quarterback with senior Lee leading sophomore Chris Relf and a trio of newcomers including true freshman, Tyler Russell one of the jewels of the 2009 signing class.
While Relf and Russell would go on to write their names in the Mississippi State record books, the 2009 season by and large belonged to the pride of Columbus, Mississippi, Tyson Lee.
Lee led the Bulldogs to a 5-7 season and one play away from a win over long time foe LSU, which would have sent the rebuilding Bulldogs bowling in Mullen's first year.
Starting all twelve 2009 games, Lee threw for 1,444 yards and four touchdowns against 14 interceptions.
Lee gave way to Chris Relf during the Battle for the Golden Egg, who turned in an MVP quality performance in relief on his way to a 41-27 victory that was not as close as the final score indicated.
Relf was the team's second leading rusher on the season behind Anthony Dixon, but it was the Montgomery, Alabama native's showing against Ole Miss that had Bulldog fans eager for the 2010 season to begin.
The Bulldogs ran for over 300 yards against the nationally ranked Rebels thanks in large part to Relf's ability to run the zone read with just enough passing to keep things honest.
A pair of touchdown tosses on that day gave Relf five for the season, which proved to be a team high despite the meager total.
What Relf showed was what the Bulldog offense could be with a real serious rushing threat behind center.
The 2010 Bulldog roster would once again only feature three scholarship quarterbacks in Relf, Tyler Russell and newly signed national record setter Dylan Favre of state champion St. Stanislaus.
Relf played in all thirteen games and was once again the team's second leading rusher behind emerging star running back Vick Ballard who joined the roster after a tremendous career at Mississippi Gulf Coast Community College.
The Bulldog offensive effort was much more balanced under Relf's direction, but Mississippi State was a running team at its' core.
Tyler Russell saw action as a sophomore, which allowed him to get his feet wet and prepare to take even more snaps in 2011.
The 2010 Bulldogs finished with a 9-4 record and a Gator Bowl blowout win over Michigan with Relf claiming MVP honors wearing Nick Bell's #36 jersey in tribute to his fallen teammate.
Some pundits claimed that Mullen's direction of Relf was the best coaching of his career to date.
High expectations greeted a 2011 roster that featured four scholarship quarterbacks with returners Relf, Russell and Favre joined by future Bulldog starter Dak Prescott.
Defenses began to load the box as their safeties crept up daring Relf to throw more during his senior season.
A brutal pair of physical losses against Auburn and LSU in a matter of five days took a physical toll on Relf that lingered through much of the season.
With defenses now keying on the run, Mullen added Tyler Russell to the mix more and more.
While Russell was not the the running threat Relf was, his ability to stretch the field in the vertical passing game forced safeties to defend the deep third.
With more room to roam, Vick Ballard rushed for nearly 1,200 yards as a senior and into the NFL draft.
Despite a challenging season, Relf led the Bulldogs to victory for the third straight time over rival Ole Miss and a win over Wake Forest in the Music City Bowl giving the Dogs back to back bowl wins since the 1999 and 2000 seasons.
Due to some attrition on the Bulldog scholarship rolls, Tyler Russell and Dak Prescott were the only scholarship signal callers on the 2012 roster.
Dylan Favre elected to transfer and the departure of 2012 signee Nick Schuessler before the beginning of fall camp left the Bulldog quarterback ranks thin to say the least.
Undeterred, Tyler Russell went on to put together one of the most prolific seasons in the history of Mississippi State football.
Russell threw for 2,897 yards and 24 touchdowns.
Bulldog fans had their first look at the future as Dak Prescott emerged as the short yardage and red zone specialist having a hand in eight Bulldog scores.
While many felt, Prescott was a signal caller more in the model of what Mullen desired in the spread offense, Russell proved that the Bulldog scheme could be tailored for success no matter what brand of quarterback barked the signals.
The Bulldogs made another trip to Jacksonville for the Gator Bowl, but saw their post season winning streak snapped at the hands of the Northwestern Wildcats.
The 2013 season saw a series of several bouts with the injury bug that forced all three scholarship quarterbacks into a starting role at different points in the season.
Tyler Russell started against Oklahoma State only to suffer a concussion that forced Dak Prescott into the QB1 spot on Dan Mullen's board.
Prescott battled through his mother's passing to give Texas A&M all they wanted before leaving the field with an ailing shoulder that would keep him out of action for most of the next three games.
The final snaps of Russell's Bulldog career were part of a come from behind effort that ended with a Damian Williams score in overtime.
Russell's final completed pass as a Bulldog was a 16 yard strike to Malcolm Johnson that put the Bulldogs inside the Arkansas 20 with around a minute left in regulation.
While Russell certainly deserved a better hand than fate dealt his senior year, he certainly lived up to his advanced billing as a four star prospect from Meridian High School.
The starting job came to Dak Prescott a year earlier than he expected, but he certainly made the most of the opportunity.
Prescott led the team in rushing with 829 yards and 13 touchdowns, while throwing for 1,940 yards and 10 scores.
The Haughton, Louisiana product also hauled in a pair of touchdown passes from Jameon Lewis just to keep things interesting.
The 2014 roster features five quarterbacks, four of which are on scholarship.
Dak Prescott, healthy once again, is in the thick of the early Heisman Trophy talk.
Damian Williams, a state champion at Arch-Bishop Rummel, did his part to send Mississippi State to a bowl game playing big roles in wins over Arkansas and Ole Miss when State simply had to have them.
Early enrollee Nick Fitzgerald led Richmond Hill High School to it's most successful season in school history last year in just his first year as a starting quarterback.
Elijah Staley, a two sport superstar, had several options to play either football or basketball on the college level, but elected to do both at Mississippi State.
Mullen began his tenure with a former walk-on as the projected starter, a back up with offers from Alabama A&M and Southern Miss and three true freshmen.
The Bulldogs enter the 2014 season with a pre-season All-SEC quarterback in Prescott and a talented group of back ups who are waiting for their turn in the driver's seat.
Needless to say, the depth chart at quarterback in Starkville has come a long way in six years.