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Tell the Truth: What is the X factor for Boston's success next season?One of our favorite parts about the Summer Forecast series is that we never know exactly how our panel of prognosticators is going to reply. You can throw out an open-ended question and get a rainbow of responses.

SUMMER FORECAST

We're breaking up the summer doldrums by trying to predict exactly how the 2012-13 season will play out for the Boston Celtics.

Or you can get just one.

And that's what happened today when we asked our hoops jury to name one X factor for Boston's success next season. Even with a plethora of possible options, the ballots all came back topped with one word: Health.

Needless to say, Boston's ability to avoid injuries will play a monster part in how the 2012-13 season unfolds. In each of the five seasons since Boston raised Banner 17, injuries have detoured the team in its quest to reclaim the Larry O'Brien trophy. Whether it was the knees of Kevin Garnett and Kendrick Perkins, or the achilles of Shaquille O'Neal, or the shoulders of Avery Bradley, the Celtics have been left to ponder what could have been with full health.

Boston appears better equipped to endure the injury bug if it lingers this season, having not only reassembled their core, but added a layer of second-level depth. Even still, the Celtics need to keep their bodies upright, particularly in late Apri and beyond.

But since you're about to read plenty about health, here's five other X factor possibilities we expected might sneak into responses:

1. Improved bench play: We've hammered this into the ground during the Summer Forecast series, but Boston absolutely needs more output from its second unit to defray the load on the starters.

2. Crank up the pace: The Celtics have added the talent around Rajon Rondo that should allow the team to run more and create easier offensive opportunities off defensive stops. Boston needs to hit the gas pedal next season.

3. On the rebound: Boston doesn't boast a lot of pure size, but it absolutely has to find a way to be more competitive on the glass. Like health, if there's been one longstanding concern for this core, it's been the team's ability to win the battle on the boards. This team needs to utilize its increased athleticism to make up for the lack of size.

4. Ubuntu! The Celtics have thrived in seasons in which team chemistry has been strong. Boston coach Doc Rivers often stressed how much he liked last year's team and, even though it wasn't the most talented group of the Garnett era, it overachieved because players accepted their roles. The core looks different without Ray Allen, but Jason Terry and his leprechaun tattoo already seem to have bought into Boston's atmosphere.

5. East not a beast? While the Atlantic Division will be stronger and the expectation is that the second tier of the Eastern Conference could take a step forward, there's no real juggernaut standing in Boston's way beyond the defending world champs. With Chicago starting the season without Derrick Rose, that could take away one big hurdle on the road to the NBA Finals. The question is whether anyone else in that second tier will emerge as a true contender, or if it's a two-horse race with Miami and Boston.

Read on for thoughts from our panel:

Greg Payne, ESPN Boston

It's health. If the Celtics can avoid the injury bug, their chances of winning it all this season are substantially better. The Celtics are coming back this season deeper and arguably more talented than they have been in the last few seasons, but a significant injury to the likes of Rajon Rondo, Kevin Garnett, or Paul Pierce could easily derail this train. You have to be most concerned about Garnett and Pierce, given their ever-advancing age. Despite both still playing at a high rate past their primes, the body doesn't heal as quickly as one gets older, so not only would an initial injury be a concern for them, but the recovery period would have to be factored in as well. Fortunately, the C's have assembled a quality bench, but the health of those players has to be taken into account as well, because if any of the immediate backups to Pierce and KG go down, it puts more pressure on those two to play more minutes, or force Doc Rivers to resort to a player buried on the bench who might not be capable of contributing as much. It's rare for a team to stay injury-free for an entire season, but if the C's can skate by without losing anyone significant for an extended period of time, they'll have as good of a chance of winning the championship as anyone.

Hayes Davenport, CelticsHub

Health is the No. 1 X factor for every team in every sport, but it looms largest for old, brittle teams who need almost all of their rotation players at full strength to contend. As you might have heard in a comments board, Boston would have won the last five championships if not for injuries: Kevin Garnett in 2009, Kendrick Perkins in '10, Shaquille O'Neal/Rajon Rondo in '11 and Avery Bradley last spring. The roster is deeper now, so they're better able to absorb the blow when a player goes down. Certain players do need to be healthy for the Celtics to make a deep playoff run, but it's a short list, probably limited to Rondo and KG. That said, the roster is still old and, even more disconcerting, some of the young players might be the most susceptible to injury: Bradley has the shoulder joints of a crash test dummy, and 19 other NBA teams didn't think Jared Sullinger's back was worth the risk in the draft. The Celtics are ready for an isolated attack of the injury bug, but they're definitely still vulnerable to another outbreak.

Tom Westerholm, Celtics Town

It's difficult to project any X factor for Boston this season bigger than health. A healthy Celtics team is a dark-horse title contender, with Kevin Garnett firing on all cylinders, Avery Bradley locking down opponents, Paul Pierce moving freely, Jeff Green completely recovered, and Chris Wilcox running the floor with Rondo -- man, the Celtics had a lot of injuries last year. Which, of course, is the foreboding thought overlying this entire roster: severe injuries to any of several players (Rondo, Garnett, Pierce or Bradley) could turn Boston from a title contender into a seventh seed facing a first-round exit. Boston needs to be injury free by the time the playoffs roll around if they want to advance past other powerhouses like Miami. And an injury-free team will be difficult to accomplish while aging stars like Pierce and Garnett are still key contributors. There is, however, a rather massive bright side: unlike last year, the Celtics have, on paper, a very solid second rotation. Jason Terry, Courtney Lee, Jeff Green, and other contributors should allow Doc Rivers to give his starters extra minutes on the bench, meaning fewer minutes and fewer potential injuries for the key cogs in Boston's system. Given last year's incredible list of injuries, it may be difficult to see the Celtics finishing the season unscathed. But it's also very possible this season could go more smoothly than the last.

Jeff Clark, CelticsBlog

Health. Period, end of story. But that's boring, so I'll talk about the next biggest factor: Jeff Green. For the most part you know what you are getting with players (provided they are healthy). Terry is a scorer, Bradley is a stopper, Lee is a little bit of both. Green is, well, he's a jack of all trades, master of none, and that's not necessarily a bad thing. If utilized properly and if he plays up to his considerable talents, he could be a super glue guy. The kind of guy that doesn't lead the team in many stats, but finds a way to help on most of the plays and puts you in position to win more often than not. On the other hand, he could very well turn out to be an expensive bust. Neither outcome would surprise me too much and how much he contributes might well have a huge impact on the Celtics this year and into the future.

Your turn: What is the Celtics' X-factor next season? Sound off in the comments.