When Tom Thibodeau left the Boston Celtics last offseason, my subjective self knew Boston’s loss would make the team irreparably worse. The Celtics could still contend without Thibs. They could still win a championship. They could still play punch-you-in-the-teeth defense. But when the league’s most successful, hard-working, knowledgeable and innovative defensive coach brings his talents elsewhere, a team will inevitably stumble, if only slightly, no matter who becomes the replacement.

The loss of Lawrence Frank to the Detroit Pistons is different. If Thibodeau is Will Hunting, the world’s most gifted mathematician, Frank is Professor Gerald Lambeau, one of the brightest mathematical minds (or one of the biggest mathematical dicks, depending on who you’re asking), but not the brightest. Had Thibodeau and Frank ever broken down defensive game film together, I imagine the scene would have gone something like this:

[Thibodeau shows Frank the way he wants to defend Kobe Bryant]

Frank says, “This can’t be right. It would be very embarrassing. Did you ever consider –”

“I’m pretty sure it’s right,” responds Thibs. “Hey look, can we do this at my Chicago office from now on, because I–I gotta knock off work to come here and the commute is killing me.”

Frank is still poring over the Kobe game plan. “Yeah, sure,” he says. “But did you think of the possibility –”

“It’s right,” repeats Thibodeau. “It’s right. Just take it home with you.”

The two continue talking, mostly about the job interview Thibodeau sent his best friend to take in his place. Frank says he will cancel the rest of Thibodeau’s job interviews and offer him a job at his office. But Thibodeau isn’t feeling it.

“Look. Maybe I don’t want to spend the rest of my fucking life sitting around explaining defensive sets to people,” Thibodeau tells Frank.

“Do you know how easy this is for me?” Thibodeau continues. “Do you have any fucking idea how easy this is? This is a fucking joke. And I’m sorry you can’t do this. I really am because I wouldn’t have to fucking sit here and watch you fumble around and fuck it up.”

The two continue their conversation in heated tones. Thibodeau says explaining defense is a giant waste of his time. Frank makes a comment or two about Thibodeau using his free time to drink with his retarded gorilla friends. Finally, Frank pores out his insecurities.

You’re right, Will,” he says. “I can’t do this proof. But you can, and when it comes to that it’s only about..it’s just a handful of people in the world who can tell the difference between you and me. But I’m one of them.”

In reality, there are more than a handful of people who can tell the difference between Frank and Thibodeau. Almost any serious NBA observer can. Thibodeau turned a starting lineup featuring Derrick Rose (who had previously been considered a sieve) and Carlos Boozer (who is still considered a sieve) into the league’s stingiest defense, for chrissake. Though there are only a handful of defensive minds smarter than Frank, there are zero defensive minds smarter than Thibodeau.

Which means the Celtics have smaller shoes to fill this offseason. The problem is, who will fill those shoes?

If Thibodeau and Frank share two traits, they are an attentiveness to defensive detail and a pitbull mentality that often leaves their neck veins bulging while they scream from the sidelines. I imagine Doc likes his top assistant coach to be screamers because he prefers a laid-back style himself. His assistants are the yin to his yang, the salt to his pepper, the left to his right. I’m not saying Doc never screams or never lays into his players — I can vividly recall one time when he called a time out just to berate Jeff Green (which I, not that it matters, loved). Still, Doc’s assistant coaches do the brunt of the screaming.

That would probably rule out Mike Woodson, who did not always register a pulse during his time on the Atlanta bench. Woodson could still possibly find himself on Boston’s short list of candidates if he does not find a head coaching gig elsewhere; he’s one of the most qualified candidates. But when I reflect on Woodson’s time in Atlanta, all I can think about is, “Iso, Joe Johnson.” Well, that and a mustache that would make this guy jealous. Presumably, Woodson is a defensive mind in the mold of Frank, and his teams, though they never did real postseason damage, achieved a reasonable amount of success. None of his Atlanta teams underachieved. But if the C’s did hire Woodson, I would not be in love with the choice.

Chris Forsberg mentioned Larry Brown as another potential candidate. The move would make sense on some levels: Brown mentored Doc Rivers early in Doc’s career. Brown has mentioned he would like to return to coaching at some point. Brown can coach basketball as well as almost anyone alive. On other levels, it does not make sense: Brown has always been one of the most controlling coaches in basketball. He wants players to play his way. He wants them to adapt to him. He loves having the wheel in his hand and being able to steer the car whichever direction he chooses. So could he adapt to an assistant coaching position? Could he give up that control he has always needed? Could he sit on the bench while Doc made the team’s final decisions? It seems like a stretch.

Almost every candidate I have seen mentioned is primarily a defensive mastermind. That makes sense, considering that Boston’s last two lead assistants have acted as de facto defensive coordinators. But Boston’s biggest weakness has been it’s offense — why not address that weakness by hiring an offensive guru?

There are reasons, but one in particular is most important — Boston’s offensive problems cannot be cured with a few new offensive sets, or even an entirely new offensive playbook. The Celtics take mostly good shots, and they make a high percentage of them — higher, in fact, than any other team in the league. Boston’s biggest offensive deficiencies involved three-point shooting, offensive rebounding and throwing enough turnovers to make me vomit on my shirt. The paltry three-point shooting can be blamed on Boston’s roster (outside of Paul Pierce and Ray Allen, the Celtics had very little three-point shooting); the offensive rebounding can be blamed on Doc’s “get back on defense at all costs” mentality (which should, and I suspect, will, change, at least to a degree); and the turnovers have always been a problem with the Big Three Celtics and likely always will. The point is, none of the issues with Boston’s offense can be solved just by hiring an offensive coordinator. So the Celtics are better off mirroring their strategy from the past four years, relying on Doc’s lead assistant to run the defense and contribute to the offense whenever he sees fit.

That still leaves the Celtics needing an assistant coach. Sadly, some of the most qualified assistant coaches have already been scooped up — Kelvin Sampson was hired by the Houston Rockets, Mike Malone (a defensive guru) relocated to the Golden St. Warriors (where he will presumably hear the phrase “Mama there goes that man” far too often), and Brian Shaw (who would have been an admirable hire anywhere) signed in Indiana after being spurned for the Lakers head job. I wouldn’t mind Brown, not at all, but I don’t see it as a realistic possibility. Forsberg mentioned the Celtics could promote from within their own organization, but Kevin Eastman and Armond Hill seem to be pigeonholed as second-tier assistants for life.

With all that in mind, I have one choice that isn’t sexy but makes a lot of sense: Eric Musselman. He fits the mold that Doc loves so much (in other words, he’s short, white and infinitely energetic). Musselman’s team’s always play defense; last year, he coached in the NBA Developmental League — his Reno Bighorns led the league in opponent’s points per game and opponent’s field goal percentage. He is a former runner-up for NBA Coach of the Year, has a world of coaching experience, and even coached under Doc Rivers when Rivers coached in Orlando. Like a well-used baseball glove, Musselman fits just right.

Any other suggestions?