In time, 2009 will be viewed as a bridge year for the Celtics. It was a year in which everyone’s worst fears were realized about their veteran core culminating in Kevin Garnett’s knee injury, and a year in which Rajon Rondo came close to realizing everyone’s greatest hopes for the future.

Garnett and Rondo are the two most pivotal figures in the Celtics universe, for while it has now been proven that the Celtics can’t go all the way without KG, it is also becoming clearer by the day that Rondo is the heir apparent.

Along the way Paul Pierce remained fixed in granite as the franchise’s foundation, Rasheed Wallace arrived and Stephon Marbury provided the strangest Celtic cameo since Pete Maravich breezed through Boston.

While 2009 fell short of the high expectations the franchise has set for itself, it provided no shortage of drama, including an epic seven-game playoff series that left observers thumbing through their Thesauruses for new ways to describe unconscious shot-making, epic buzzer-beaters and endless overtimes.

Here are the top 10 most important moments, events and developments of the past calendar year.

1. KEVIN GARNETT’S INJURY

It was oddly fitting that Garnett’s breakdown happened under the cover of darkness in the late night of a game in Utah, because everything about it became shrouded in mystery.
 
What almost no one outside the inner Celtics sanctum knew at the time was that Garnett had been struggling with his knee for most of the season. There had been subtle signs — a decline in free throw attempts, more jump shots than post-ups — but nothing so pronounced as to rouse deep suspicion.

In the aftermath, the lack of media access to Garnett and the small scraps of information provided by the team led to all kinds of wild rumor and innuendo about the true nature of the injury, and even speculation that KG would make a dramatic triumphant return at some point during the playoffs. He didn’t, of course, and that more than anything was proof of his importance to the team’s title hopes when they fell to the Magic in the conference semifinals.

It also provided fodder for skeptics who questioned Garnett’s pain tolerance, which is the price he pays for the walls that he has chosen to erect to protect his privacy. Not that it seems to bother or affect him in any way, and indeed such skepticism neglects to include the thousands of minutes that he has logged throughout his career when he was no doubt not feeling his best. 

What isn’t in dispute is that after an uneven preseason and early part of the regular season, Garnett has returned to more or less the player he was before the injury, which has coincided with the return of the Celtics to the upper tier of NBA title contenders.

But the impact of Garnett’s injury has lingered in the team’s roster decisions both in the short and long term and will continue to do so for the foreseeable future.

2. RAJON RONDO’S EMERGENCE AND CONTRACT EXTENSION

There was a point during the summer when hardly a day went by without a new Rondo trade rumor. He was going to Detroit, or maybe it was Memphis. Stories emerged of his petulance and his tardiness before a playoff game, but like the endless Garnett talk, the rumors proved to be little more than a smokescreen, or perhaps a veiled message to the young prodigy that it was time to grow up.

Whatever the true nature of the summer buzz, the Celtics showed their hand by delivering a five-year extension to Rondo at the beginning of the season and the early returns indicate it may have been a bargain.

Rondo still has work to do — most notably at the free throw line — but he is becoming the core component the team will build around in the post Big 3-era and an ever-more important piece of the current puzzle. His extension also presumably takes the Celtics out of the free agent frenzy this summer, although one should never discount Danny Ainge’s willingness to get creative.

3. ENTER RASHEED

After their bench proved to be more hindrance than help, the Celtics wasted little time in targeting Wallace in free agency, dropping a three-year deal for the full mid-level exception on the combustible big man. Wallace’s arrival not only helped secure the bench, a sore spot throughout the 2008-09 season, it also helped mitigate the potential loss of Garnett and extended the veteran era beyond this season.

Between Garnett, Rondo and Wallace, the Celtics have committed just under $40 million annually to those three players through the 2011-12 season. How that affects the futures of Ray Allen and to a lesser extent Paul Pierce remains to be seen, but it indicates a willingness to wring every last drop out of the Big 3.

On the court, Wallace has been as advertised: a sometimes maddening enigma, but an enormously resourceful and multi-talented player who has helped turn the second unit from a weakness into a strength, while racking up technicals and sound bites at an alarming and often amusing rate.
 
4. PAUL PIERCE AS ELDER STATESMAN

He has played at a higher level than any other current Boston athlete since he first arrived in 1998. Who would have guessed that earlier this decade? At some point in the future Pierce will take his place among the Celtics greats, if he isn’t rightfully there already.

On a roster full of players who hunger for respect, Pierce has appeared to find peace with himself and his place within the league’s hierarchy. Always a phenomenal performer, Pierce has paradoxically seen his image grow as his numbers and responsibilities have lessened on the court. 

Pierce has also found his place as the Celtics conscious, working out long hours mostly out of view from the public and handling the role of team spokesman with aplomb. If Garnett is the backbone and Rondo the kinetic energy source of the Celtics, Pierce is the beating heart and the living soul of the team. 

5. RAY ALLEN SHOWS HE STILL HAS SOMETHING LEFT

There is a minor debate brewing in the stat-geek world as to when basketball players tend to peak in terms of age. Some say 27. Others say as early as 24 or 25. Absolutely no one says 33.

Allen didn’t exactly peak in 2009, but he did post career highs in True Shooting Percentage, Effective Field Goal Percentage and Offensive Efficiency Rating, which is a fairly impressive late-career spike and not at all typical for NBA players, let alone shooting guards a few years removed from ankle surgery.

Allen’s 2009-10 season has seen him revert to his previous levels, which are still quite good at any age, but the previous season has had the effect of making it seem like Allen has lost a step. That’s wrong and also unfortunate timing for Allen.

This is the last year of Allen’s contract and he and the Celtics will have a decision to make at the conclusion of the season. Will they extend the Big 3 era further, knowing their core pieces will be in their mid 30’s and will Allen be willing to accept a contract that reflects that reality?

That’s still to be determined, but Allen has already proven the trade that laid the foundation for this era was well worth it, regardless of how the story ends.

6. BIG BABY DRAMARAMA

As eventful as Rondo’s summer was, no one had a more fitful offseason than Glen Davis. Finding no love in a free agent market that couldn’t even find an offer for fellow restricted free agent David Lee, Davis fretted and vented about his situation on Twitter before finally returning to the Celtics on a two-year deal.

Just as that had settled down, Davis found himself in an unfortunate confrontation with a friend in the early-morning hours before the season opener, which left him in a cast and unavailable to play until Christmas Day.

It still remains to be seen if the strides Davis made in the 2009 post-season culminating in his game-winning shot that beat the Magic in Game 4 in Orlando was a sign of things to come, or just a big tease.

7. KENDRICK PERKINS STATES HIS CASE

It’s unfortunate that Perkins still has not found the respect throughout the league that he has been searching for, but his performance against Dwight Howard in the playoffs should stand as the moment when Perkins emerged from his supporting role as fifth wheel into something larger.

Playing with an arm he could barely lift over his head and with precious little support from the bench, Perkins stared down the NBA’s signature center and almost lifted the Celtics into the conference finals on his broad, but weakened shoulders.

With a revamped offensive game and a menacing defensive presence, Perkins is on the verge of joining Rondo as the key members of the next generation of Celtics.

Respect will come.

8. THE BRIEF, BIZARRE AND UNSATISFYING STEPHON MARBURY ERA

For a good chunk of the winter, the Celtics pursued the erstwhile Starbury as he extricated himself from the messy remains of the wreckage left in New York by Isiah Thomas. Marbury finally joined the Celtics in February amid much fanfare and even more questions. Would he tear apart the Celtics, or would he and KG ride together again as in their halcyon days in Minnesota? And how would he affect Rondo?

In the end it was all sound and fury signifying nothing more than a rusty past-his-prime guard. If anything, Marbury tried too hard to ingratiate himself into the Celtics unselfish system, passing up shots he used to take without hesitation and playing the role of passive distributor rather than taking hold of the Celtics second unit and injecting some much-needed offensive creativity.  

Marbury’s moments were brief — a sudden burst of energy in a dramatic Game 5 comeback win against the Magic being the lone highlight – and his lasting impression may have been turning down a one-year contract offer and then descending into UStream madness.

Ainge had struck gold with late-season additions Sam Cassell and P.J. Brown the previous year, but his attempt to replicate that move with Marbury and Mikki Moore ended in disappointment in Marbury’s case and lots and lots of fouls in Moore’s.

9. THE IMPROBABLY WILD, BUT ULTIMATELY MEANINGLESS FIRST-ROUND SERIES WITH THE BULLS

Heading into the last day of the regular season, the Celtics seemed set to play the Philadelphia 76ers in the first round of the playoffs. But after the Sixers became just the second team to win in Cleveland and the Bulls tanked their finale at home against the Raptors, the stage was set for the most sublimely ridiculous and entertaining first-round playoff series in NBA history.

It featured seven games, seven overtimes and a battle between Ray Allen and Ben Gordon for the unofficial title of most clutch former UConn long-range bomber. It had Rondo averaging a triple-double and serving notice that Derrick Rose’s time had not yet come, and Tommy Heinsohn screaming for Joakim Noah to go back to France. There was bad blood, real blood and even a tooth from the mouth of Chicago’s Brad Miller sacrificed for the cause.

It was in a word, awesome.

But if it proved anything it was simply that the Celtics would not surrender their championship crown without a fight, even without Garnett. There was value in that, valiant as it was, but the relatively low stakes of the first-round series meant that its legacy will ultimately be relegated to the second row of league history.

How much the series took out of the Celtics is open for debate, but they became for a brief moment sympathetic figures until their Game 7 collapse at home against the Magic in the next round, proving that this series was a pyrrhic victory at best.      

10. TOM THIBODEAU REMAINS

More than half the teams in the NBA have had coaching changes since the Celtics captured the 2008 NBA championship and Tom Thibodeau remains in the chair next to Doc Rivers, one step removed from the top spot.

The architect of the Celtics smothering defensive philosophy, Thibodeau’s return after interviewing for head coaching jobs in Philly and Sacramento was one of the more understated and important outcomes of the summer.

An assistant as universally respected as Thibodeau can’t stay without a head-coaching gig forever, but as long as he remains the Celtics are fortunate to have him.