You know what happens when you’re rooting for a creaky but lovable basketball contender? You relish the big victories. All of them. Every single one. You know the season could collapse at any time, and you’re perfectly aware that a torn meniscus, calf tear or herniated disk might sucker punch your season when you least expect it. It’s a little liberating, actually. Your expectations are low because you shouldn’t expect anything at all.

And with that said I actually expected the Celtics to prevail in Miami last night. I really did. Had you told me as recently as six weeks ago, “The Celtics are going to win in Miami in mid-April, and by the way, you will expect it to happen,” I would have assumed that LeBron and Wade had crashed on Bobby Petrino’s motorcycle or something. Miami IN Miami? No way.

How did we get here? It wasn’t that long ago that the great Bob Ryan described Boston’s situation as “Year Five of a Three-Year Plan.” A five-game losing streak had dropped the C’s to a measly 15-17, as a-hole writers like myself were grabbing shovels and burying the team. With trade rumors swirling around All-Star Rajon Rondo — planted by other teams hoping to cause chemistry problems and drive down his price, by the way — the Celtics won three straight, then throttled the Knicks on a Sunday ABC home game that we’ll always remember as Rondo’s “Look, You’re Not Effing Trading Me, You’d Be Insane” game (18 points, 20 assists, 17 rebounds).

The next two weeks were fairly fascinating: The Celtics hoping to rebuild around Rondo and cap space, while steadfastly refusing to give away their valuable veterans. Before the Clippers game at Staples, less than three days before the deadline, I spent 25 minutes talking to Ainge and fellow BYU grad Michael Smith, now a broadcaster for the Clippers. It was becoming more and more clear that Ainge should keep the team intact; the day before, they played extremely well in a last-minute Lakers loss, and it’s not like anyone in the East was pulling away from them. Making the decision easier: Nobody was offering anything decent for Pierce (owed $32 million total in 2013 and 2014) or Garnett (whose $21 million cap figure made it near impossible just to match salaries in a trade). Allen’s expiring contract and crunch-time pedigree made him more appealing, but no contender had the right assets to pursue him. At one point, Smith brought up a young player who could, conceivably, have been the centerpiece of an Allen trade. Danny just started laughing.

“We’re not trading Ray Allen for [the player’s last name],” Danny said. “Come on! It’s Ray Allen!”

You need to know two things about Danny Ainge. First, he’s probably the most confident person currently running an NBA team. Any and all criticisms bounce right off him. He just doesn’t care. As someone close to him explained (I’m paraphrasing), Danny has won at everything his whole life. He was an incredible high school athlete. He was a star in college and married the prettiest girl there. He played TWO professional sports. He played on those championship teams with Larry and Kevin. He pulled off the KG trade and won in 2008. This is not someone who worries about what other people are saying. So even if “What the hell is Danny doing?” became a permanent conversation after last year’s Kendrick Perkins trade, that groundswell never intimidated him into making a panic deal. Second (and this ties into the first point), Danny has no fear whatsoever. Of anything. The joke within Celtics circles is that Danny would trade his mother if it helped the team.

Anyway, I left our conversation thinking that Danny honestly didn’t know how the deadline would play out. Chatting with Wyc Grousbeck a few minutes later, the Celtics’ owner seemed similarly confused. Why break these guys up without a really good reason? What’s the point? After the Celtics played a superb game against the Clippers, I came to my own conclusion: “The Celtics are what they are: old, proud, stubborn and (mostly) fun to watch simply because they know each other so well Leave them alone and the 2012 Boston Celtics will go down swinging. That’s all we know, and frankly, that’s good enough for me.”

I flew to Oakland for the Warriors game two nights later, if only because the trade deadline was the following day, and, I mean not to sound corny, but you never know with this stuff. If this happened to be the last night for the Pierce/Rondo/Garnett/Allen foursome, I wanted to be there. They prevailed by two behind another throwback KG game (24 points, 11-of-15 shooting), which made little sense because Garnett looked salad-fork-in-the-back-finished as recently as January. I remember when Bird’s body broke down (a four-year spiral that started during the ’88 Detroit series and crested in the 1992 playoffs, when he could barely move), when McHale’s ankles slowly betrayed him (1991), when Parish just couldn’t fight off younger leapers anymore (1993). You usually know with these things. You just do. And I would have wagered anything that Garnett was more finished than Desperate Housewives.

Guys were jumping over him (shades of Parish), his jumper was flat, and worst of all, he looked absolutely miserable. Like he didn’t want to play basketball anymore. Even during his signature staredown/pointing routine before tip-offs at home games, you never felt like his heart was totally in it. When his game inexplicably rebounded in February (17.6 PPG, 9.3 RPG, 54% shooting), everyone attributed it to Rivers moving him to center. News flash: Garnett had been playing center since the Perkins trade. Everyone was just pretending otherwise for KG’s sake. He’s weird about this stuff. It’s the same reason Garnett likes to be listed at 6-foot-11 when he’s really 7-foot-1, or Tim Duncan always wants to be listed as a forward even though he’s been playing center for the past seven years. You don’t ask questions with big men; you just do whatever it takes to keep them happy.

You know what really fueled Garnett’s resurgence? He’s a competitive MF’er. That’s really it. The lockout ended, he couldn’t get going those first few weeks and then, suddenly, the “KG is done” talk started, and even worse, opponents started treating him differently. They stared him down after dunks, talked shit to him, accorded him little to no respect. He probably remembered doing the same to Patrick Ewing, Derrick Coleman, Chris Webber or whomever over the years and thought to himself, I’m not ready to be That Guy yet. The flame started flickering again. As he told WEEI’s Paul Flannery two weeks ago, “I hear you all calling me old. I hear you calling me, um, older. Weathered. I’m motivated. It don’t really take much to motivate me, man. I’m older in basketball years, but in life I’m thirtysomething.”

The trade deadline passed with Rondo reinvested and Garnett reenergized. You know who else stuck around? The second-leading scorer in Celtics history, Paul Pierce, who stunk in February (16.4 PPG, 39.5% FG) and inadvertently murdered his own trade value. Remember when New Jersey’s bid for Dwight Howard fell through, then they panicked and swapped a top-three protected 2012 pick to Portland for Gerald Wallace, and everyone said, “Wait a second, why would someone give up a top-three protected pick for the third-best player on a sub-.500 team?” Not reported at the time: New Jersey could have landed Pierce for that same pick, only they chose Wallace because he was a full five years younger.

Little did they know no. 34 was slowly morphing into Paul Pierce again: In 23 games since March 2, he’s averaging a 22-6-3 with 46/38/85 shooting splits and looking no different than the Pierce from 2008-11. If you’re scoring at home, suddenly Pierce, Rondo AND Garnett were playing their best basketball again. But this still-creaky Celtics team wouldn’t have morphed into a contender without three other developments.

1. The league’s six best perimeter defenders right now, in some order, are LeBron, Tony Allen, Andre Iguodala, Shawn Marion, Iman Shumpert and (drumroll please) Avery Bradley. You might remember me writing on February 10 that “I watched Trick or Treat Tony for the first five years of his career. I watched [Bruce] Bowen for the first three years of his career. Bradley is just as good of a one-on-one defender as they were at the same point in their careers. All Bradley needs to do is learn how to shoot corner 3s and he’ll have a 15-year NBA career and play a significant role for at least one contender. I swear, I’m not going Heinsohn on you.” So the defense wasn’t a shock.

But when those jumpers started going in? That was a shock. Doc started playing him. Everything snowballed. Avery started driving to the basket and making plays. Celtics diehards started glancing at each other and saying, “Wait a second, is Avery Bradley good or am I crazy?” Near the end of March, Allen missed a few games and inadvertently transformed Bradley’s career; with the kid playing 40 minutes a game, suddenly the Celtics were causing turnovers, getting easy fast-break points, locking dudes down and basically wreaking havoc. They haven’t played defense like that in three years. And it’s contagious. People were taking charges, switching at the perfect time, flying from the weak side to block shots everything just snowballed. And it happened because of Garnett and Avery Bradley. He’s for real. Do I trust the kid defending Rose or Wade in a playoff series? Yes. Yes I do. So there.

2. Bradley’s coming-out party can be explained — it came down to confidence and minutes. But Stiemsanity? I have no answers. Greg Stiemsma never averaged more than 12 minutes per game in any of his four Big Ten seasons. (Seriously. Look it up.) He bounced around for four solid years after college. He looked decent in the preseason, earned the Tommy Heinsohn Seal of Approval (getting compared to Bill Russell), quickly lost his mojo and seemed headed for a low spot in the All-Time White Celtics Rankings right between Andrew DeClercq and Brett Szabo. Then, Jermaine O’Neal went down, and so did Chris Wilcox and just like that, the Stiemer was playing 19 minutes a game, blocking shots (he’s averaging two a game since the All-Star break), running the floor, making open 15-footers, taking charges, banging bodies and doing everything you’d ever want from a backup center, with the added bonus that Boston fans loved him more than horny middle-aged housewives love Fifty Shades of Grey.

Does any of this make sense? NOOOOOOOOOOOOOOO! It makes no sense whatsoever! Again, he’s playing 19 minutes a game in the NBA when he never played more than 12 minutes a game in college. Did I mention that he’s doing this with a badly sprained foot? And that he can’t practice? And that he was wearing a walking boot for a couple of weeks? Let’s just move on before we jinx Stiemsanity.

3. I already made Doc Rivers’s case as “Coach of the Year” in last week’s column, a moment that gave the Mayans extra conviction that 2012 is going to be their year. But you know what’s been even more incredible than Bradley morphing into a young Joe Dumars, Rondo shrugging over trade rumors and somehow raising his game, Pierce and Garnett playing like they just flew to Germany with Kobe, or Stiemsanity sweeping the nation? What about Doc finally (and belatedly, but whatever) figuring out the value of a locked-in playing rotation?

Even when they won the 2008 title, Doc was routinely playing 11 guys in one half — he just couldn’t grasp the concept of “stick to eight or nine guys, make sure everyone knows their minutes, don’t deviate from this” (or as Vinny Del Negro calls it, “The Opposite of What I Do”). Now, you might say Doc didn’t have a choice this year — after a few putrid Danny signings, the Celtics have seven reliable players (Rondo, Pierce, Garnett, Allen, Bradley, Stiemsma and Brandon Bass), with three key bench guys (Jeff Green, Chris Wilcox and Jermaine O’Neal’s Corpse ) missing and Mickael Pietrus still recuperating from a scary concussion last month. You can’t play fewer than eight guys, so Sasha Pavlovic has gotten Pietrus’s “Backup Perimeter Guy” minutes by default.

But here’s the thing about the NBA you only need eight guys every night. Just look at how Doc handled Tuesday night’s Miami game. Pierce and Rondo played 40 minutes each; Bass played 39; the old guys (Allen and KG) played 35 and 33, respectively; Bradley played 25; Stiemsanity played 20; and Pavlovic played eight. Nobody else played. Doc never had fewer than two of the Pierce/Rondo/Allen/Garnett quartet out there at all times. With Rondo and Pierce sitting in the fourth quarter, Miami made a charge as I was muttering, “Uh-oh Doc’s going to wait two minutes too long we’re about to give this game away ” when BOOM! Doc felt the game slipping and brought back the starters at the 9:30 mark. Allen made a backbreaking three, then Garnett headed down to Bosh’s Pit and started swishing old-school KG jumpers — not one, not two, not three (copyright: LeBron), but four in a row! — and before you knew it, the Celtics were ahead by double digits again. They never really looked back.

How are they playing defense this well? Why aren’t their jumpers flat anymore? Why is Rondo clicking so well with the vets again? Can they really be peaking during the most brutal part of their schedule (11 games in 15 nights)? Are they evolving into this year’s version of the ’99 Knicks, the late bloomer who meshed at the perfect time and sneaked into the Finals? I’m prepared for anything. The players looked like they were drifting apart in January and February; in Miami, they were hugging and slapping palms like a team that (a) totally believed in themselves, and (b) absolutely, unequivocally believed that they were winning that game.

Now, if you’re a Miami fan, you come away from that game thinking, That’s a fluke loss, there’s no way they can shoot 61 percent against us four times in a playoff series. And you’d be right. But that wasn’t the lesson from that game. The Celtics know who they are. It’s Year 5. They trust each other. They trust their coach. They trust the three newer guys, and when Pietrus comes back, they’ll trust him again, too. They know where to go and what to do. They can score and get stops. They will fight. They will keep coming.

What does Miami know about itself? Let’s start backward. LeBron and Wade are having superb individual seasons. In the open floor, they rank among the most breathtaking combinations ever (if not no. 1 all-time), but in the half court? It’s still “Dueling Banjos,” something that hasn’t changed since day one. Meanwhile, poor Chris Bosh got eviscerated by Garnett last night, yet another ignominious moment for someone who had already squandered any and all “Big Three” privileges. He’s just not that good. Their veterans (Mike Miller, Udonis Haslem and Shane Battier) all peaked three to four years ago, especially the 33-year-old Battier (December’s most overrated signing), who can’t even crack 35 percent from 3 (all of them wide open, by the way). Their 2011 point guard situation is just as messy as 2011’s situation; sometimes Mario Chalmers shows up, sometimes he doesn’t, and their two rookie backups (Norris Cole and Terrel Harris) can’t be trusted. And just last week, Erik Spoelstra benched Joel Anthony for Ronny Turiaf. Yeeesh.

So if you’re scoring at home, we’re less than three weeks from the playoffs and Spoelstra has no idea

A. Which six guys he can trust after LeBron, Wade and (by default) Bosh.

B. Which five guys should be finishing every game.

Seems like two pretty big questions, no? The latest media narrative has been, “Maybe Miami should just play LeBron at point guard,” something the numbers back up (especially Tuesday night’s stats). Really, the narrative should be, “How the heck does this team not have an identity yet?” Last night, they played their butts off and STILL lost. I remember thinking that Boston couldn’t beat Miami if LeBron had one of those Mega-LeBron games — you know, 36 points, seven rebounds, seven assists, a couple of fast break dunks/blocks, a couple of 3s, some post-up moves, just one of those games when he’s involved — and that’s exactly what happened last night. Guess what? They still lost.

We’ll remember it as one of the single most meaningful victories of the Three-Year Plan That Lasted Five Years: the night Boston officially threw its hat into the 2012 title race. It doesn’t totally make sense, but then again, none of this makes sense. Rondo could be playing for the Hornets. Pierce could be stuck on the Nets. Doc could be announcing games with Mike Breen and Jeff Van Gundy. Bradley could still be buried on the bench. Danny could have panicked right before the deadline and had a fire sale for Garnett and Allen. It’s a swollen list of “what ifs,” and just about every one of them went Boston’s way.

At least for now. You never know with those creaky but lovable basketball contenders. We’ve reached this specific point six other times in Celtics history. Russell’s last two squads (’68 and ’69) won consecutive titles while running on fumes. The same thing happened with the last good Havlicek-Cowens team (’76). The last two Bird-McHale-Parish efforts (’91 and ’92, two severely underrated teams) fell short because the Legend just couldn’t stay healthy. More recently, the 2010 squad came within Perkins’s knee injury and Artest’s improbable no-no-yes 3 from stealing a championship. Now, the fellas from 2012 are making a run. Nobody saw this coming. And really, that’s the single best thing about it.