They were one game away from the NBA Finals. They had two chances, actually. And one of those two elimination games was on their home court. Chew on that, then spit it out and scratch you head in amazement at this little reminder:

This was the Celtics just six months ago, in case you’ve been paying too close attention to them recently and forgot. Yes, the same Celtics who staggered through the first two months of this season, which is creeping toward the midway point. The same Celtics who began raising questions about ever being in the title mix again in the Kevin Garnett-Paul Pierce-Rajon Rondo era.

The same Celtics who should thank the basketball Gods for being in the East, a conference where most of the decent teams have dealt with as many flaws and funky stretches as the Celtics lately.

Well, here in early January, after showing too many red flashing lights, they’ve finally arrived at the moment of truth. We now get to see if the Celtics are who they claim to be: proud, stubborn and finally complete now that the roster is healthy for the first time all season.

“In some ways, we’re just now getting our season started,” said coach Doc Rivers. “It’s taken longer than I would’ve liked, but hopefully it’s starting to happen for us.” 

They’ve sprung to life lately, impressively so. In the last five days, they've easily played their cleanest basketball of the year. They’ve now won three straight and beaten the Pacers, Hawks and Knicks, three of the top four teams in the East, all looking down on Boston, if only for the moment. They played 2008-level defense against the Pacers, shocked the Hawks by rallying from 19 down, then won a physical and overheated game in New York without Rondo, who served a one-game suspension Monday for being rude to a ref. Basically the Celtics put those teams on blast and reminded them that another team, a familiar one, is equipped to swap places with them in the standings very soon if this keeps up.

“It’s nice, but we gotta keep doing it,” coach Rivers said, “or this doesn’t mean as much.”

They also welcomed back starting guard Avery Bradley and, now, finally get to see the team they envisioned on Opening Night. Their next five games are all at home, all winnable. That’s some rather vivid, if not convincing, evidence swinging in their favor, and strongly hints that the stench of a 14-17 start could be vapor once All-Star Weekend rolls in.

“Nobody in this locker room ever thought we couldn’t turn it around,” said Pierce. “That’s not how we think. Never entered our minds. We’ve been around too long for that.”

They’re now at .500 and feeling not too terrible about the mediocre start -- especially once you consider all the issues they had, such as the new pieces added over the summer (ask the Lakers how long that process takes) and injuries to key players. 

“Our (best) lineup hasn’t even played one minute together, so I’d like to give that a shot,” said GM Danny Ainge.

All those mitigating factors still didn’t prevent the inevitable questions about a shakeup -- as if that were suddenly necessarily. Certainly the next six weeks will let Ainge know whether the Celtics are indeed back to being a dangerous team in the East, or if this is just a mirage. Any changes would be minor, anyway. Unless some team calls them with a crazy offer, the Celtics will not trade Rondo. He means too much to Garnett and Pierce, both of whom are 99-percent certain to remain in Boston in the last two years of their respective deals. And the Celtics intend to ride it out with those three because of their chemistry and proven history together.

Without trading Rondo, there is no major deal because the Celtics have no other major assets, only spare parts. And besides, the luxury of playing in the East affords them the comfort of patience. Why panic when you’ve just beaten the three teams who trail the Heat, the team you took to seven games last summer? 

Keep in mind, the Celtics have played only three games with their full squad. Bradley now joins Rondo and provides Boston with a young and frisky backcourt that will get in your grill on defense and juice up the running game. Why not see what a healthy and complete Boston team can do first, then react? 

Crazy, when you think about it, how the Celtics have had anything but the luck of the Irish ever since this Golden run began five seasons ago. Sure, they won a championship in Year One of the new Big Three, but the mini-dynasty never materialized, through little fault of their own. Garnett pulled up lame in the playoffs following a 62-win season. The next year, they went to a Game Seven with the Lakers and played it without Kendrick Perkins, and couldn’t catch a break on a night when Kobe Bryant shot 6 for 24. In 2011, they simply ran into a younger version of themselves against Miami, but returned last season to take a 3-2 series lead on the Heat, which needed a historic performance by LeBron James to pull out the East title. 

That’s five years, one championship, two trips to the Finals, three trips to the East finals and five appearances in the East semis. Crummy luck probably cost them at least one more championship, if not two.

“I sometimes think about what we could’ve done had we been healthy every season,” Rivers said. “You can’t help but think about that.”

And we should add the Celtics played Miami last summer without Bradley, who might have made a difference in a tight series. They’re now getting him back from a shoulder injury and hope he can be just as productive, in a different way, as the player he replaced -- Ray Allen. Bradley isn’t the same outside shooting threat, but brings better defense and quickness.

This really isn’t totally about Bradley, anyway. Or Jason Terry, struggling (42 percent shooting) in his first year in Boston. Or Jeff Green, who the Celtics hope can be the solid third or fourth option that his talent suggests (rather than just a classic ‘tweener who can’t play either forward position very well). Or rookie Jared Sullinger or Courtney Lee. All are important in their own supporting-role ways, but won’t dictate the winning and losing of big games.

Really, it’s about the usual suspects, the holdovers from the championship season: KG, Pierce, Rondo, Rivers. The good news for the Celtics is KG is still woofing -- witness his back-and-forth Monday with Carmelo Anthony, complete with a few well-timed sharp elbows ('Melo allegedly sought out KG after the game, but Rivers remained mum about what went on). Pierce can still score and is capable of dropping 30 on any team at any moment. Rondo is leading the NBA in assists. And Doc is Doc, one of the better coaches around. This core is still productive and edgy and well-tested, the kind of foursome that knows how to go deep into the post-season.

Funny thing: A year ago, the Celtics started 15-17 and twice lost five in a row. And you know what? Same situation happened then as now. Teams like the Pacers and Bulls (pre-Derrick Rose injury) started getting comfortable in the East penthouse, and even the redesigned Knicks were making noise about ending the Celtics’ streak of Atlantic Division titles at four.

“It’s not like we wanted to get into a rut so we could fight our way out,” said Rivers. “We were in one, made some changes and they worked.”

As it turned out, Boston claimed a fifth division title and then forced LeBron James to play the game of his life in the playoffs. How stunning would it be if they make it a sixth in April? 

Mindful of what the Celtics just went through in December, knowing they have what it takes to create abrupt change, Pierce said: “It’s a long season. Don’t forget.”

That’s the mistake we make about the Celtics.