Brad Stevens is going from a mid-major to the major leagues.
There is no debate within basketball that he can coach, having taken Butler to consecutive NCAA championship games with players who schools such as Kentucky and Kansas weren't exactly lining up to sign.
But coaching in college has hardly ever guaranteed success in the NBA, definitely not lately and certainly not with the type of situation Stevens will be walking into in Boston.
The Celtics are going to be young - younger even than the boyish-looking Stevens - and not expected to be competitive. Kevin Garnett and Paul Pierce will be gone, it's unknown when or even if Rajon Rondo will be back, and even a playoff berth might be out of reach for a franchise that had grown used to competing for championships again.
Success at a school such as Butler was easy to judge. If Stevens won 20 games, got the Bulldogs into the NCAA tournament and knocked off a school from a power conference, that was considered a great year.
But in the NBA, where multiple, established coaches just led teams to their best seasons ever and still lost their jobs, Stevens will have to prove he's more than just a guy who can oversee some big upsets.
The Celtics believe he is.
"Brad and I share a lot of the same values," president of basketball operations Danny Ainge said in a statement.
Las Vegas certainly wasn't swayed. The Celtics' odds to win a championship remained at 100 to 1, the same as before Stevens was hired, according to the gambling website Pregame.com.
The Celtics have had plenty of success with guys from small schools. Ainge himself played at BYU, and they won big with another guy from an Indiana mid-major, a pretty fair player from Indiana State named Larry Bird.
But they also know as well as anyone how quickly a college genius can turn into a professional flop.
They went nowhere with Rick Pitino when he left Kentucky in 1997, before he went back to college and won last season's national title at Louisville. Once the Celtics missed out on Tim Duncan in the '97 lottery and never found the type of talent Pitino had his choice of in college, the Celtics never contended.
Remember when a frustrated Pitino once said that Bird, Kevin McHale and Robert Parish were never walking through the locker room door?
Well, neither are Garnett, Pierce and Ray Allen.
That makes the 36-year-old Stevens' challenge a daunting one. He has to try to win with a rebuilding roster that's expected to lose. He has to get through to Rondo, a brilliant point guard recovering from a torn ACL whose mood swings can rub anyone the wrong way.
If the Celtics were still a title threat, would Doc Rivers really have wanted out of his contract to go somewhere else? Would Ainge really have signed Stevens, respected as he may be in the coaching ranks, when Coach of the Year George Karl was available, as were Lionel Hollins and Vinny Del Negro after leading the Grizzlies and Clippers, respectively, to their best seasons ever?
Maybe so, given the changes to the coaching ranks lately.
Teams are willing to take chances on younger guys who haven't gone from successful playing career to longtime assistant before proving they deserve an opportunity.
Erik Spoelstra was the model, working his way up from the Miami Heat's video department to two-time NBA champion as coach. Indiana's Frank Vogel is another young coach who got his shot when Bird hired the former advance scout, and Vogel had the Pacers within a game of the NBA Finals.
Stevens' success at Butler, where he won 77 percent of his games, did wonders for mid-majors. The NCAA tournament selection committee grew more willing to extend bids to smaller schools over mediocre ones from the power conferences after watching teams like the Bulldogs prove they could compete with any of them.
Now he can have a similar influence in the coaching ranks. If he shows there's no difference in coaching at legendary Hinkle Fieldhouse as there is at the new Boston Garden, that solid X's and O's work just as well in the Atlantic Division as in the Atlantic 10, other guys like him may start getting their shots.
They already are. Vogel was only 37 when the Pacers turned to him in 2011, so he knows Stevens can get it done.
"The Celtics got one heckuva basketball coach," he said through the Pacers. "Congrats to Danny Ainge and Brad."