The inner workings of that clock have a great many gears.
One is the decision to be made on Paul Pierce. Boston's captain has a $15 million payday next season, but the team can also buy him out for just $5 million. That would send the long-tenured Celtic to free agency.
Another decision includes Kevin Garnett's fence-sitting on retirement and a no-trade clause. Garnett has the right to veto any trade team president Danny Ainge makes. He also wouldn't surprise anyone with a retirement after 17 years of service. The man recently celebrated his 37th birthday.
A smaller gear is the health of Rajon Rondo. Though he seems to be continually planting just one foot in superstardom, a ton of upcoming events will hinge on his return from an ACL injury. The Celtics just trudged through half a season without him, something the veterans don't wish to do again.
Those three gears, along with a couple smaller treads, are putting pressure on head coach Doc Rivers.
It has been well over a month since the Knicks ended the Celtics' season, but Rivers is still offering only cryptic replies to the question: Are you coming back next year?
In a recent conversation with the Boston Globe's Gary Washburn, Rivers was again evasive to that increasingly important question. He is constantly couching the hopes of Celtics fans with phrases like "I'd rather not say," or that he will let them know "soon."
Rivers could be waiting on those other gears to turn just a little bit more. The Pierce decision must be made by June 30, which is three days after the NBA draft.
What he would be walking away from is still up in the air. Should Garnett and Pierce return for one more year, Rivers would feel far more obligated to return. Those are his guys, and he loves nothing more right now than sharing his basketball knowledge with them.
However, there is still a chance neither of them returns. The prospects of coaching a young team built around Rondo and Jeff Green may not be as appealing.
Who is most likely to be with Boston next season?
The one thing he would absolutely be walking away from is $21 million. Rivers' contract goes for another three years at $7 million a pop. That is a healthy chunk of change, and far more than Rivers could immediately make in the broadcast booth. It's also more than he ever made as an NBA player.
Things aren't as simple as returning to coach the Celtics without Pierce and Garnett. A whole chunk of what Rivers has learned and implemented as a head coach over the last eight years goes out the window when those two leave. There is no telling if his current coaching style and systems will mesh with a new group, or that he will be able to change on the fly.
Garnett changed the culture of the Celtics, while melding his own defensive style with that of Rivers and former assistant Tom Thibodeau. Pierce has been the end-all, be-all of the Celtics offense since Rivers arrived in 2004. As much as Rondo has been utilized in recent years, Pierce's scoring ability has carried the Celtics franchise for more than a decade.
The Celtics would need a new defensive system. Unless Garnett is traded for a post player, the cupboard in Boston is bare. Rivers stares at the prospect of teaching Jared Sullinger, Brandon Bass and a possible No. 16 pick the ins and outs of a new system without the aid of Garnett and Thibodeau.
Offensively, the system will run through Rondo at the point. There is some experience there, as that is the way things were going prior to his injury. However, Green isn't Pierce. Celtics fans will find that out in a hurry if Green is left without Pierce on the roster this coming season. He proved a lot with his play against the Knicks in the postseason, but still lacks the offensive subtleties of Pierce's game.
It is a lot tougher to preach an offensive system to new players, featuring Rondo at the point, when there is no perimeter game from Garnett, or creative shot-making from Pierce. It is an offensive and defensive overhaul that Rivers would be taking on.
If this is the case with his current situation, can you blame Rivers for weighing his options this long? He has spent eight years learning the ropes of being head coach of one version of the Celtics. If Pierce, Garnett and Ray Allen are all gone, that version is over.
Rivers has a fairly famous reputation for holding back his rookies and young players, pushing guys through early, like Rondo and Sullinger, only by necessity. That necessity will be ever-present for Boston after the Pierce-Garnett era comes to a close.
He's got a son playing ball professionally in New Orleans now, and another with his basketball future up in the air. There is also a lot more golf to be played in the sunshine of Orlando than the snow of Boston.
Still, Ainge seems to believe Rivers is returning. He recently denied the Brooklyn Nets the opportunity to speak with him concerning their vacancy. That sent a message to the handful of teams searching for a coach now. Rivers is, at the moment, off-limits.
Ainge knows what is making Rivers so hesitant. The two have been together for eight years. Since he is planning on his coach returning, he must be on the verge of making the right move with Pierce and Garnett.
Washburn told "Mike and Mike in the Morning" on ESPNRadio that Rivers returning was probable, but "not a slam dunk."
It may not be a dunk, but his return has to be a Pierce jumper at the elbow: lessening in frequency and smoothness, but still the closest thing to automatic you'll find in Boston.