Keys to a Boston Celtics Upset of LeBron James and the Cleveland Cavaliers

The NBA regular season has drawn to a close, and the Boston Celtics are gearing up for a first-round matchup with LeBron James and the Cleveland Cavaliers. 

Almost nobody thinks Boston has a chance to win this series. That's understandable: The Cavaliers are significantly more talented than the Celtics, and Cleveland is a popular title favorite. James remains arguably the world's best player. It will surprise nobody if Boston gets swept.

But this is the playoffs, and anything can happen. The Celtics finished the season on a six-game win streak, they won 17 of their final 24 games and they have absolutely nothing to lose. Making the playoffs was a welcome surprise for a team that many expected to tank. 

So while a Celtics upset is unlikely, it's not impossible. Here are three keys to a Boston victory.

Coaching

Any discussion of the 2014-15 Celtics starts with second-year head coach Brad Stevens, whose obvious brilliance has left Celtics fans giddy. Coaching is likely Boston's biggest advantage in this series. 

Few expected Boston to compete this year, let alone make the playoffs. If you had told me before the season that Boston would get rid of Rajon Rondo and Jeff Green, lose Jared Sullinger to injury, trade a first-round draft pick for Isaiah Thomas and make the playoffs as a No. 7 seed (behind meaningful contributions from Jae Crowder and Evan Turner), I would have chuckled. 

But that's what happened, and it started with coaching. The Celtics have evident chemistry, they play hard and their rapport with Stevens is clear. 

Stevens' coaching acuity is perhaps most evident during inbounds plays. As ESPN Boston reporter Chris Forsberg noted on Twitter, Boston was among the league's most efficient teams in terms of after-timeout possessions. 

Stevens' inbounds plays have been beautiful to watch, and many have come in clutch moments. Check out the clips below:

To be fair, Stevens' counterpart in Cleveland, David Blatt, has done a good job. In his first season as an NBA head coach, Blatt was burdened with the impossibly high expectations that come with LeBron, Kevin Love and Kyrie Irving. He has effectively juggled egos and managed the team through important mid-season roster changes. His team is a clear title contender.

But frankly, earning the No. 2 seed in the anemic Eastern Conference while starting three of the league's 25 best players isn't as impressive as what Stevens has done.

Stevens' strategic genius, coupled with his team's evident chemistry and nothing-to-lose mentality, is an important obstacle for the Cavaliers. 

Defense

Boston is not a defensive juggernaut. They rank 13th in adjusted defensive rating, per Basketball-Reference.com, and, more importantly, they have an obvious lack of rim protection. Cleveland will start two of the league's best rim-attackers in Irving and James. 

But Boston's defense could prove stauncher than expected in two different ways. 

First, as Grantland's Zach Lowe noted earlier this week, the Celtics are extremely tough in transition. Boston usually has some combination of Turner, Crowder, Marcus Smart and Avery Bradley on the floor. Brandon Bass is an underrated athlete, and Kelly Olynyk and Jonas Jerebko—while not exactly defensive stoppers—are long-armed and rangy. 

That combination of athleticism and length means that, in transition, Celtics players can often simply guard the opposing player they're closest to. That's a big advantage: Boston allowed allowed fewer fast-break points per game than every other team except Milwaukee, per TeamRankings. Given that Cleveland ranked just 20th in fast break offense, Boston should be able to prevent the Cavaliers from earning easy buckets in transition. 

Second, the Celtics boast two of the league's best perimeter defenders in Bradley and Smart. Smart, in particular, has earned raves for his aggressive style of play. He refuses to back down from anyone, even MVP candidates like James Harden:

Bradley is listed as day-to-day on Boston's injury report but is expected to play. If he does, his often-frenetic defense—shown in the clip below—should help Boston put pressure on Irving. Slowing down Irving will make a big difference in Boston's upset hopes. 

Isaiah Thomas

Finally, we come to Thomas, whom the Celts acquired from Phoenix in February. Thomas has been a revelation in Boston, averaging 19 points and 5.4 assists per game since joining the team. 

He has quickly meshed with his Boston teammates after a frustrating stint in Phoenix. And while Thomas remains deficient in several respects—particularly on defense—he has been absolutely critical to Boston's offensive success. 

He can pass:

He can dribble:

And, despite standing just 5'9", he can finish around the rim:

There isn't much more to say here. Thomas has proven himself an uber-talented (if streaky) offensive player. If he plays well, the Celts will compete. 

A Boston victory in this series is improbable. But they have a magician of a coach, tenacious perimeter defenders and a dynamic offensive spark plug in Thomas. Plus, they like each other and play hard. 

Either way, this Boston team is fun to watch. Given their youth, that should continue for long after the 2015 playoffs.