If Doc Rivers leaves, who should replace him as head coach?

Is Lawrence Frank the best available successor?
The "Doc Rivers might not be coming back" rumblings just won't go away, and now ESPN's Chris Broussard has got us thinking it could be more reality than rumor.  With that in mind, here are some names of potential coaches the Celtics may want to consider if Doc actually does calls it quit.  I see three different ways Boston could go (and this would all depend on how Doc's departure effects Paul Pierce and Kevin Garnett; if they're gone as well, a bigger rebuilding project would almost definitely lead to a smaller name for the new head coach):

Stay in house: Currently the top three assistants are Mike Longabardi, Armond Hill, and Kevin Eastman, but none of them have ever really been considered as head coaching candidates.  Then there is Tyronn Lue, who generated some interest from the Raptors last month.  Lue is just 36 years old with only two seasons under his belt as an assistant, but recently retired guards with minimal experience turned head coaches are definitely the trend of the moment in the NBA (Mark Jackson in Golden State, Jacque Vaughn in Orlando, Jeff Hornacek in Phoenix, and maybe Jason Kidd in Brooklyn?).

Go with a young up-and-comer: Obviously Lue fits on this list as well.  Indiana assistant Brian Shaw has been a hot name this offseason, but the former Celtics point guard had a very rough departure from Boston once upon a time.  Miami assistant David Fizdale has also generated some buzz, but could anyone really envision the C's hiring a coach from the Heat?  Then there's the possibility that former Suns GM and current TNT analyst Steve Kerr might be interested in giving coaching a try, and he clearly fits the Jackson-Hornacek-Kidd mold.

Hire an established veteran: This is the most likely scenario, and there are a lot of choices out there.  First there are the Van Gundy brothers.  Jeff recently mentioned that me might be interested in the Nets job, and Stan seems unlikely to be satisfied with his current gig of coaching clinics in Montreal (although he also said last month that he will not coach in the NBA in 2013-2014).  Just two days ago Memphis opted not to re-sign Lionel Hollins, a surprising move considering he'd just led the Grizzlies to their most successful season in franchise history.  Byron Scott is out there with 13 years of head coaching experience, although his .444 career winning percentage is less than inspiring (he also appears close to taking the L.A. Clippers job).  Recently fired by the Clippers, Vinny Del Negro is probably an even less enticing option than Scott.  One intriguing possibility is Lawrence Frank, who was let go by the Pistons in April.  Frank took the Nets to Atlantic Division titles in 2004 and 2006, and spent 2010-2011 as Doc's top assistant in Boston.

I also feel obligated to mention the old and very experienced guys who probably won't be interested in rebuilding the C's: After being fired by the Nuggets, George Karl is available, but all indications are that he'd only want to take over a situation with the chance to succeed immediately.  At 71 years old, longtime Jazz coach Jerry Sloan is in the same boat.  The only thing Phil Jackson is doing for work these days is a book tour; how amazing would that be if Boston could convince him to coach again?  And if we're really getting crazy, it's been almost a year since Larry Bird stepped down as Pacers team President for health reasons.  I wonder if he's feeling better?  Sacramento just tried to lure him back unsuccessfully; but come on, that's the Kings, not the one and only Boston Celtics.

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