Believe it or not, the 2018-19 NBA season has already reached the halfway point.

Any trends that have gone on this long can now be classified as full-fledged surprises or disappointments.

Maybe we're still intoxicated by the positivity of beginning a new year, but we're going to focus solely on the surprises here. (You're welcome, Washington Wizards.) While there are different degrees of surprises, each fits the model of comfortably outperforming preseason projections.

Oh, and we're only looking at clubs we expect to be in the 2019 postseason. As blown away as we've been by the Sacramento Kings (and, at times, the Luka Doncic-led Dallas Mavericks), we're bearish about their playoff chances and therefore leaving them off the list.

Brooklyn Nets

The Brooklyn Nets haven't had a winning record since the likes of Kevin Garnett, Paul Pierce and Andrei Kirilenko roamed the Barclays Center. Their last playoff team was coached by Lionel Hollins and led by Joe Johnson, Deron Williams and Brook Lopez.

It's been a minute.

There was little reason to think the drought would end this season. Brooklyn went 28-54 last season and seemingly had an inconsequential summer. During the draft, the organization threw darts at Dzanan Musa and Rodions Kurucs. The free-agency haul was "highlighted" by Ed Davis and Shabazz Napier.

Vegas looked at this roster and saw a 32.5-win team. Fast-forward to now, and rival coaches see the same group as a potentially pesky playoff opponent.

"I'd be surprised if this team's not in the playoffs," Boston Celtics coach Brad Stevens recently told reporters. "They're awfully good. ... I love the way they play. They play hard, they play together. Everyone knows what they're supposed to do, and they do it every night."

D'Angelo Russell has never looked better by volume or efficiency. Spencer Dinwiddie continues to shatter his career ceiling. Joe Harris is clearing 50 percent from the field for the first time and nearly doing the same from distance. Kurucs has emerged as the latest hidden gem, offering the versatility of a modern wing with the size of a small-ball center.

The Nets, who once looked like tanking candidates at 8-18, have sprinted through a 13-4 stretch over the last month, the same point at which Kurucs cracked the rotation. Brooklyn now appears playoff-bound, and Kenny Atkinson should find his way onto most Coach of the Year ballots.

Denver Nuggets

The Denver Nuggets might feel like they're above the "surprise" threshold since they opened the campaign with a 9-1 sprint and seemingly haven't let up since. The standings (28-12) and stat sheet (plus-5.5 net rating) both agree this is the best team in the Western Conference.

But even the most ardent Nuggets backers might admit they didn't see this coming.

This wasn't a playoff team last season, as their 46-36 finish left them one game shy. Their biggest offseason investments were in-house, like Nikola Jokic's $148 million max extension and Will Barton's four-year, $54 million pact. Otherwise, they hoped for bargains in the medically red-flagged bin (Michael Porter Jr. and Isaiah Thomas) and rewarded summer-league standout Monte Morris by converting his two-way contract into an NBA deal.

Vegas felt another down-to-the-wire playoff fight would be coming, setting Denver's bar at 47.5 wins. The Nuggets might beat that by double digits based on their 57-win pace.

Their offense is as explosive as expected (sixth in efficiency), powered by Jokic as the rare point center and Jamal Murray as the fearless, ignitable perimeter scorer. But it's the dramatic improvement on defense (from 23rd to ninth) that makes you think this group could be more than a regular-season wonder.

"Denver is deep, versatile, balanced ... and has two guys capable of putting the team on their back against even elite defenses," Dan Devine wrote for The Ringer. "Sounds like a recipe for a long postseason run."

Indiana Pacers

For the second straight season, the post-Paul George Indiana Pacers are shattering preseason expectations. After last year's 48-win breakout, oddsmakers challenged them to sustain that success with a 47.5-win over/under. Indy has responded by completing the first half of its schedule at a 54-win pace.

The upswing is impressive enough. But maybe the biggest surprise in the Circle City is the method of success. The Pacers have moved forward without checking off multiple boxes you may have assumed would be necessities for further growth.

Victor Oladipo hasn't continued his ascension; rather, he's taken a half-step backward. Potential No. 2 scorer Tyreke Evans has instead landed at No. 6 and could fall further if he can't correct his sub-40 percent shooting. Fellow offseason imports Kyle O'Quinn and Aaron Holiday have struggled to find consistent minutes. The offense has gone from being the NBA's 11th-best unit to sitting 16th.

How are the Pacers making this work? For starters, their defense has jumped from above-average (12th) to elite (second), thanks in no small part to Defensive Player of the Year candidate Myles Turner. The fourth-year big man is tallying an NBA-best 2.8 blocks per game, posting a career-high 22.1 defensive rebounding percentage and nearly doubling his previous best with a 4.6 defensive box plus/minus.

"The organization came to me and said, 'Your offense is gonna come, but we need you to be the best defensive player in the NBA,' and I really took that to heart," Turner told reporters in December.

It hasn't hurt that Bojan Bogdanovic is obliterating his career shooting rates from the field and three, or that Domantas Sabonis is converting an absurd 62.1 percent of his field goals. While the Pacers could use more spacers (fewest made threes), their inside-the-arc dominance has given them the Association's third-best field-goal percentage.

Los Angeles Clippers

The second All-Star voting returns are in, and the Los Angeles Clippers don't have a single representative among the West's top 10 guards or frontcourt players. That probably surprises no one, save perhaps for owner/superfan Steve Ballmer. This conference boasts the entire 2017-18 All-NBA first team and six of the second- and third-teamers, after all.

The Clippers are willingly—and, they hope, temporarily—without a star. They traded Chris Paul in June 2017 and moved Blake Griffin the following January. With no household names remaining, the semi-featured roles are now split among the mostly anonymous core of Tobias Harris, Danilo Gallinari, Lou Williams, Montrezl Harrell and rookie Shai Gilgeous-Alexander.

And yet, only four teams in the Western Conference have a better winning percentage than L.A.'s .585 mark.

"I've got to admit I didn't see the Clippers playing at their current level," NBA.com's Steve Aschburner wrote. "They've sewn together a laudable quilt of scorers, facilitators, defenders, role players and leaders. They hit their three-pointers at a good rate and tend to the arc at the other end, while taking care of business at the foul line."

This is some of the best work head coach Doc Rivers has ever done, and not just because he's working without a star. This organization has massive plans for the upcoming offseason, and because of them, most of this roster is playing on expiring or short-term contracts. That can be the recipe for a franchise to fracture, but chemistry is one of the driving forces behind the Clippers' success.

Of course, it doesn't hurt that Harris is suddenly a 21-point scorer shooting nearly 50/40/90. Or that—knock on wood—the injury bug is finally leaving Gallinari alone. Or that Williams is as productive per minute as ever, Harrell is becoming one of basketball's best bargains and Gilgeous-Alexander appears one of the most NBA-ready rookies in this class.

Milwaukee Bucks

Granted, there were reasons to feel bullish about the Milwaukee Bucks. Each season seemingly brings Giannis Antetokounmpo one step closer to basketball-world domination, and he entered this one with a more favorable system (put together by new coach Mike Budenholzer) and better-fitting supporting cast (loaded with shooters).

That said, the Bucks were coming off a 44-win effort. A leap could've nudged them into the upper 40s, but Vegas set a more conservative mark of 46.5. Expectations called for something between a playoff hopeful and a pesky first-round opponent.

Milwaukee didn't get the memo. Behind a supercharged Giannis, a never-stop-launching offensive approach and a defense that jumped from serviceable (18th) to suffocating (third), the Bucks have managed to control this entire campaign. No one has a higher winning percentage than their .725. No one owns a better net rating than their plus-9.2.

Antetokounmpo is on a short list of MVP candidates and might deserve to be the favorite. He's good-to-great at everything, save outside shooting. In any stat category other than three-pointers, he's probably high on the leaderboard with top-15 rankings in points, rebounds and blocks. When he's on the floor, the Bucks bulldoze opponents by 11.3 points per 100 possessions.

"I definitely think it's our belief inside this locker room, and a lot just around the league, that we have the best player in the league right here," Brook Lopez said, per ESPN.com's Tim MacMahon. "He does it in so many ways. He makes so many of his players better. He's all over the court constantly. It's so impressive to watch every night."

Milwaukee must keep progressing to pursue its biggest goals, but it's surprising to see how much and how quickly this club has improved.

Statistics courtesy of Basketball Reference and NBA.com and accurate through games played Thursday.

Zach Buckley covers the NBA for Bleacher Report. Follow him on Twitter: @ZachBuckleyNBA.