I’m all in. I’m convinced. I believe.

The Celtics have one more memorable playoff run left in them.

And for that reason, with Rajon Rondo, Paul Pierce, Ray Allen and Kevin Garnett all on board, there’s no reason they can’t make things very interesting in the East this spring. Don’t trade them. Give them more help.

Danny Ainge should go all out to make sure this team has every legitimate chance to take out LeBron and the Heat and Rose, Noah, Deng and the Bulls.

I’ve been scolded by a certain columnist colleague for even dreaming of the possibility of a Game 6 at the Garden with either the Heat or Bulls.

“There’s no way they even get to a Game 6.” “Trags, did you not watch last season when LeBron took over in Game 5?” “Who’s going to guard Derrick Rose?” And on and on.

I’ll admit it.

I thought this team was toast two weeks ago. The C's looked old, played hurt and seemed worn out.

But remember, Rondo was frustrated by all the trade rumors that have been swirling around him and was suspended two games for a momentary loss of his senses. They had a fairly brutal road stretch leading into the All-Star break.

They lost five straight. Rondo suspended. KG hurt. Pierce overloaded with scoring obligations and Jermaine O’Neal rendered useless by a chronic wrist injury. “I don’t know what I’m going to do with Jermaine,” Ainge told The Big Show on Thursday.

Then, before the players headed their separate ways for the break, Garnett spoke to the team in one final desperate attempt to reach into the hearts and souls of his teammates. It’s worked.

“It says we’re fighters,” Garnett replied on Tuesday when asked what the two OT wins this week show about this team considered too old to have a shot at playing in June. “We’ll grind this thing out and see what we can do. If you know anything about us, or anything about our history for the last five years, is that we grind and we’re going to work and push this thing to see how far we can take it.”

There are those in this space who have written that the window isn’t closing, it’s closed. I couldn’t disagree more.

These are the 1987 Celtics that lost to the Lakers in the NBA finals, not the 1988 or ’89 collection that was too old and broken down to cope with the Pistons. That ’87 group had made it to four NBA finals, winning three. This group has made it twice and won once. But upon closer review, these Celtics have been legitimate contenders every year they’ve been together. It didn’t look that way for the first 30 games this shortened season. But that changed after the break and after Garnett’s speech.

They have shown guts and determination in back-to-back overtime games to begin this week. They won five straight and, lo and behold, have the chance to win the Atlantic Division, assuring them of at least a top-four seed in the Eastern Conference playoffs when they begin in late April.

Forget Wednesday’s 32-point loss to the division-leading Sixers in South Philly. Everyone knows the older Celtics had just won two remarkably emotional overtime games in three days -- including the win against all odds Tuesday at home against the Rockets -- and had zero in the tank. Even the ’86 Celtics would take one for the team and get obliterated once in a while in a road game.

Colleague Paul Flannery will be with the Celtics on their West Coast road trip this week. Flannery will be keeping close tabs on Ainge at every turn leading up to next Thursday’s trading deadline. We both agreed that this trade deadline will not only set the course for the rest of the season but for the next five years.

After Sunday’s thrilling OT win over the Knicks, Flannery suggested the Celtics have one more run in them. I agree.

So, what will Ainge do?

Short answer: He’s far more likely to add a piece like Michael Beasley than he is to trade one of the Big Three or Rajon Rondo. Why? Because Beasley is a big body who can be had for little in return and because as great as Rondo has been playing, there doesn’t appear to be a general manager ready to give the Celtics anywhere near enough to offset losing the quarterback of the offense and the best player on the team.

As for the others:

Paul Pierce has rededicated himself to rebounding, and it paid big dividends in the wins over the Nets and Knicks. He has looked rejuvenated after the break, and with just six weeks left in the season he can smell the playoffs again. He has recovered nicely from his heel injury in camp and looks ready to score, night in and night out. Sure Ainge will “listen” to offers for Pierce. Then again, he’ll listen to a call for Rondo for a lottery pick. That ain’t gonna happen. Pierce is too much the heart and soul. And any trade of Pierce for less than a superstar leader in return makes rebuilding next year that much tougher.

Ray Allen is having the best year of his Hall of Fame career from long range. Yes, the man who holds the all-time record for 3-point field goals is even better this season. It’s a testament to his work ethic and dedication. At just $10 million, his contract is the most tradable of the Big Three, but, as he showed late against the Knicks and Rockets, he is also the most indispensable long-range threat the C’s have. His threat on the court gives the Celtics the spacing they need to open lanes to the basket for Pierce.

Kevin Garnett stepped up before the break and told the locker room in no uncertain terms that this was likely it for the group. He wanted to make it clear that he was going to leave everything he had on the court and he expected everyone else in the locker room to do the same. He has played with the same vigor, posting four straight double-doubles before Wednesday’s blowout loss in Philly.

The point is: If Rondo, KG, Pierce and Allen are on the same court, let alone the same page, the Celtics are as good as Miami or Chicago. The four of them have the ability to slow the tempo down enough to frustrate LeBron, D-Wade and Bosh.

As Flannery pointed out to me this week, the real wild card here is the Celtics going out and getting a big like Beasley to provide some beef off the bench. Love Greg Stiemsma, but that won’t cut it in May. That’s where I think Ainge’s focus should be. Give these Celtics the best chance against the Heat and Bulls. They deserve that much.

Doc Rivers is the consummate leader as a coach, and his staff will be prepared. There’s no worry there.

Ainge sits courtside and knows all of this. He realizes if the Celtics just miss the playoffs in the next two or three years it won’t matter if he makes one final push with this group.

As much as he desperately wants to win now, Ainge gets paid to manage the assets of the Celtics and build a winner year in and year out. Has he seen enough to think this group has one final run? I think so.

Doc was being honest when he told Dennis & Callahan Thursday morning that he’d be surprised if a significant deal was made near the trade deadline. No doubt, he’s been assured by Ainge that, barring any NBA GM offering Derrick Rose, Blake Griffin or Kevin Durant, the Big Three and Rondo aren’t going anywhere.

That’s good, because this group has a chance. I believe it. Do you?

To the Trags Bag:

It’s a two-parter.

1. What will Danny Ainge do and what should he do at the trade deadline?

2. Should Patriots fans fear Peyton Manning back in the AFC East with either the Dolphins or Jets?

@nesportsfan83 would it be really smart or really dumb to get rid of rondo while he is so hot?

At this point, barring any GM blowing away Ainge with an offer he can’t refuse, it would be really unwise to deal Rondo since the players have finally convinced themselves that they can make noise.

@drjefflo Whatever happened to Marquis Daniels? Is he in the Rivers witness protection program?

Not the witness protection program, only the “trailing by 30 on the road in the fourth quarter program,” i.e., Daniels has still not fully recovered all of his defensive skills that made him such a bench asset two years ago when the C’s came within a fourth-quarter meltdown of Banner 18. Daniels is not in Doc’s “rotation of nine” as he called it after Tuesday’s game. And don’t expect that to change without injury anytime soon.

@SteveB7SFG Fear it? No way, I welcome it, football is so much better with him in it. Who would rather watch Manning or Sanchez, Henne?

@PatsPropadanga I dont fear it. I'd enjoy it. The Pats need a new rivalry, and Brady vs. Manning twice per year would be a treat. All for PM in Miami

To both, I agree. The Patriots and Bill Belichick have seen enough of Peyton Manning that they won’t fear him personally, but clearly, with Manning back in the division, either team figures to be right there with the Patriots, especially the Dolphins, who showed at the end of the season that their defense is on the rise.

@PatriotsChick87 Fear is not a word we use, we're not afraid of him.

But respect is definitely in play. And that’s what the Dolphins will immediately command if they successfully enlist the services of the Manning, who now has one fewer Super Bowl rings than his baby brother. More than anything, what Manning can do is disrupt a defense with the best of them with his audibles at the line of scrimmage.

@0_LayDX If Peyton came to Miami, do you think that will affect BB draft or FA signings since he has to face Peyton twice?

Good question. Short answer: Not that much. Aside from wanting to address safety, Bill Belichick will still look to beef up his defensive line with Vince Wilfork a year older and the team still looking for more upfield pass pressure from the base front. That said, Belichick has always regarded Manning as a “divisional” foe in that each knows the other’s strengths and weaknesses. So, what you’ll definitely see is a renewed emphasis on exotic defenses when/if Peyton plays in South Beach.