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Nobody knows how close Kevin Durant was to signing with the Boston Celtics other than Kevin Durant. But right before the four-time scoring champion shoved the NBA’s hope for competitive balance off a rooftop by teaming up with Steph Curry, Draymond Green, Klay Thompson and the Golden State Warriors, Boston was ostensibly in the mix as his most logical destination.

Despite their inability to lure that franchise-altering, expectation-shattering talent, the Celtics head into the 2016-17 season with a conference finals-worthy mix of depth, talent, coaching and cohesion. The Warriors and defending champion Cleveland Cavaliers set the bar high above the NBA's 28 other teams, but Boston’s nipping at their heels; its flight from ground zero to the clouds is moving faster than anyone could've anticipated.

Last year, the Celtics had one of the NBA's five best defenses, adopting a modern style that promises to breed real success once they acquire a bit more experience and talent: move the ball, shoot threes, don't let up on the defensive end and play with a relentlessly uptempo pace.

Durant thinks the Celtics have a bright future, and the Boston Herald's Steve Bulpett explained why they were one of his final choices:

Those who doubt the lure of Brad Stevens and his potential to attract free agents will be disappointed by Durant’s reasoning in choosing the Celtics as one of just six teams with whom he’d even meet. If it wasn’t clear from the unsolicited comments from opposing players in praise of what the Celts are building, Durant put it simply. “I just like the way they play,” he said. “I like their coach. I feel they have some good pieces.” Numerous sources and reports said at the time that Durant’s decision eventually came down to staying with the Thunder or moving on to Golden State, though we’d heard the Celts’ agreement with Atlanta free agent Al Horford made him stop and think.

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And that brings us to the All-Star Boston actually did land over the summer.

Biggest Offseason Move

The organization’s most timely and pivotal free-agency signing in (at least) several generations, Al Horford inked a four-year, $113 million contract back in July.

His on-court impact in Year 1 will be massive on both ends—from ingenious passing, to positional versatility, to his selfless nature, to being an upgrade over Jared Sullinger in almost every way imaginable—but Horford's off-court influence is almost equally meaningful, particularly regarding what it does for Boston's perception around the league.

He chose the Celtics over his Atlanta Hawks, the Oklahoma City Thunder and Washington Wizards. All those teams would’ve had at least one top-20 player already on board. Boston has no such thing, yet the four-time All-Star locked his eyes on the future, endorsing a front office, coaching staff and budding core that managed to win 48 games last season with the ninth-youngest roster in the league.

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"Even when I was with Atlanta, and we beat the Celtics in the playoffs, I was very impressed with how hard the guys played, and how good the team could be," Horford said at Celtics media day. "We all know the situation with their flexibility and future draft picks. That was there, but for me just the guys that we have here, the group this season, that’s what I felt good about."

One of basketball's most consistent and reliable two-way big men for a decade, Horford was one of 10 players in the entire league to average at least 15 points, seven rebounds and three assists last season. According to Bleacher Report Insights, he was one of just four centers (Karl Anthony-Towns, Robin Lopez and Mason Plumlee) to start in all 82 games.

Dating back to 1983-84, the Celtics have never had a power forward or center start all 82 games.

Horford's credentials are worth a standing ovation, but so is his game's ongoing evolution. On a career-high 3.1 attempts per game, he shot 34.4 percent behind the three-point line last year, adding a new dimension to his skill set. He'll now infuse Boston's offense with another big who can space the floor.

It's something that Celtics head coach Brad Stevens was excited about on media day.

"[Horford] made sure he changed as the game changed, and ultimately really did a great job at making that transition look really easy...I’ve watched him shoot it in individual work and he’s a guy that can really shoot the basketball, and we’ll need him to shoot. We’ll want him to stretch the floor for us, for sure."

Rotation Breakdown

The Celtics return almost every key player from last season's team, which sets up a positional logjam at several key spots, particularly in the overstuffed frontcourt.

PG SG SF PF C Isaiah Thomas Avery Bradley Jae Crowder Amir Johnson Al Horford Marcus Smart Gerald Green Jaylen Brown Kelly Olynyk Tyler Zeller Terry Rozier R.J. Hunter Jonas Jerebko Jordan Mickey Demetrius Jackson James Young

Though a bit of a headache, deep rosters aren't the worst thing in the world, particularly when they're loaded with growing players who fight for consistent minutes. So long as everyone buys in and puts the team's success ahead of their own opportunity, it should be a smooth season.

Elise Amendola/Associated Press

Isaiah Thomas is the 5'9" offensive catalyst who made his first All-Star team last season. More than a sparkplug in his first full year as Boston's starting point guard, the Celtics averaged an abysmal 98.7 points per 100 possessions whenever he didn't play, per NBA.com.

With Thomas on the court, Boston's offensive rating shot up to 106.4, which would've ranked seventh in the league. By his side in the starting backcourt is Avery Bradley, a rabid but undersized 2-guard who's best suited off the ball as a spot-up threat.

Bradley redistributed his shot selection and launched the most threes of his career last year. Unfortunately, he only shot 31.3 percent from the corner and showed zero growth as a secondary creator. He must improve in both areas if Boston's offense is to be more explosive, but Bradley earns most of his money on the other end. He was named to the All-Defensive First Team last season, and continues to provide some of the most aggressive on-ball defense the NBA knows.

On the wing, Jae Crowder emerged as a two-way force last season; he's a borderline All-Star and integral chess piece who operates at both forward spots and shot a respectable 33.6 percent behind the arc. Defensive versatility is one of Boston's great strengths, and Crowder is its firmest muscle—he sticks to quicker guards and withstands the blunt force of larger forwards.

In the frontcourt, Horford, Amir Johnson and Kelly Olynyk (who's still recovering from offseason shoulder surgery) are three complementary staples of Stevens' rotation, but it's undetermined how the Celtics will juggle shot-blocking Jordan Mickey, semi-dependable Tyler Zeller and versatile Jonas Jerebko with any leftover minutes, especially considering this team will likely prefer to play small.

One option may be starting Johnson at power forward, then subbing Marcus Smart in for him around the seven-minute mark, immediately going small before reinserting Johnson in the second quarter as Boston's backup center.

Reasons for Confidence

Boston is a pseudo-contender, which is ridiculous when you realize that only three years ago they had to bottom out and start all over. The additions of Horford and third overall pick Jaylen Brown should make the team even more athletic, dynamic and intelligent than it was last year, but nearly as crucial as internal growth.

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Terry Rozier (22 years old), Smart (22), Olynyk (25), R.J. Hunter (22), Mickey (22), Crowder (26) and Bradley (25) are all still improving, while veterans like Thomas (27) and Johnson (29) aren't declining just yet. It's possible some of these guys plateau or even disappoint, but that'd be unusual given their age and experience level.

Even if some take a step backward, it's almost impossible to picture Boston's fifth-ranked defense not improving with Horford and Brown on board. Smart agrees, telling Bleacher Report at Celtics media day how much easier Horford will make life for Boston's perimeter defenders.

"Al’s been a guy that, just like me, prides himself on defense. We have guards that are very aggressive and tenacious to get into guys. Now we have a big that can help us, so we can be as aggressive as we want to."

That's a terrifying thought for opposing ball-handlers, considering only two teams forced more turnovers per 100 possessions than the Celtics last season, per NBA.com.

Overall, they don't have enough talent to take down the Cavaliers or Warriors in a seven-game series, but they're versatile enough to match up well against almost any other team in the league.

Reasons for Concern

Can they shoot, and who will fill Evan Turner's shoes?

Boston had the 13th-best offense in the NBA last season, but its love for three-pointers was not reciprocated by the three-point line. They were 11th in three-point attempts and 28th in three-point accuracy, with 7-foot Olynyk as the only player to finish above 40 percent beyond the arc.

The Celtics also finished 29th in effective field-goal percentage on catch-and-shoot attempts, per NBA.com. Horford's mid-range jumper has long been as reliable as the rising sun, but it's not enough to offset dour outside shooting from half the roster—Smart can't shoot 25.3 percent from beyond the arc again, especially in the playoffs.

Boston likely added Gerald Green to help solve this problem, but the career 36.1 percent three-point shooter is now 30 years old and hit just 32.3 percent from deep with the Miami Heat last season. He isn't the answer.

Thomas and Crowder both finished with impressive true shooting percentages—mostly thanks to how much time they spent at the free-throw line—but it's unlikely Boston's offense will ever generate enough points unless those two take and make smarter looks from the outside.

NBA.com

Beyond shooting, the Celtics lost one of their primary ball-handlers in free agency. It's a crushing blow for a team that now has only one established shot creator in its backcourt. Turner didn't shoot threes, but he could separate from his man whenever he wanted—an invaluable asset in crunch time. He also finished second on the team in assists, as someone who could thread the needle running a pick-and-roll or drive-and-kick to spot-up shooters on the weak side.

NBA.com

"I think it’s a big loss because of the way he handled the ball, and the big shots he made late in games," Stevens said at Celtics media day. "His positional versatility defensively, his everyday workman-like attitude in the gym. He just has a great way about him and we’re going to have to replace that."

Horford will help lubricate this offense's gears as a post scorer and playmaking roll man, but the Celtics need Smart, Crowder and/or Rozier to step up into a larger role with the ball in their hands. If they aren't up to the challenge, Stevens may need to stagger Thomas and Horford's minutes, ensuring at least one is on the floor at all times to prevent a drought.

Player to Watch

The Celtics have nearly a half-dozen players on their roster who could break out this season—from Smart to Rozier to Olynyk. But the most interesting commodity is naturally the one who hasn't logged a single NBA minute: 19-year-old Jaylen Brown.

Kim Raff/Associated Press

He's in a rare situation as a third overall pick who's heading to a team that's already established as opposed to a rebuilding dumpster that can promise 30 pressure-free minutes a night. But Brown's athleticism and physical attributes could be a huge plus for a team that wants/needs as many versatile defenders as it can get.

He may not crack the rotation as a rookie, but doing so would add a new dimension Boston didn't have last season. If he can score in transition, get to the free-throw line and knock down some open jump shots, all the better.

Predictions

Barring a midseason trade for someone like Jimmy Butler or Paul George, this team doesn't have enough talent to compete with the Warriors and Cavaliers when games matter most.

But they're built to roll through the regular season, with the ability to play small and fast or big and slow.

Horford and Thomas may both end up in the All-Star Game, and Stevens now has a stable of young athletes to mold and incorporate into his system. Expectations are high coming off a 48-win season, and general manager Danny Ainge still has several desirable assets to dangle for that third star. But in the meantime, being rock-solid in multiple areas probably isn't enough for the Celtics to raise their 18th banner in 2017.

Instead, it's Eastern Conference Finals or bust.

Final Ranking: 55-27

Division Standing: 1st

Playoff Berth: Yes

B/R Leaguewide Power Rankings Prediction: 5th