Heading into the season, conventional wisdom said it would take a miracle for the Miami Heat to avoid winning the Southeast Division. But six games in, the scenario no longer seems so far-fetched. While the Heat are limping along at 4-3 with Shaquille O’Neal sidelined by a sprained ankle, the Washington Wizards have raced out to a 5-1 start that has marked them as one of the league’s most surprising teams.

Washington won its first three games, but few fans raised an eyebrow because the opponents were the Raptors, Knicks, and Magic. Throw in a home loss to the Clippers early last week, and Washington looked to be the middling, fringe playoff team that everyone had expected since training camp.

But it only took a single weekend for the Wizards to change that impression dramatically. First came a 137-96 waxing of Seattle on Friday night. Washington led by 25 before halftime and hit the century mark with over two minutes left in the third quarter.

However, as I noted in Friday’s column, blasting the Sonics to smithereens is no longer a newsworthy event. Last year’s Northwest Division champs are a complete miss right now, and after all of six games new coach Bob Weiss already is on thin ice. So even a 41-point pasting of the Sonics might not have garnered much attention.

But beating the world champion Spurs the next night? By double figures? That’s a different story. Washington’s 110-95 win on Saturday, in the second game of a back-to-back no less, served notice that the Wizards are a rising force in the East. Washington held Tim Duncan to 3-for-18 shooting and rode a scorching Gilbert Arenas (41 points on 15-of-20 shooting) to bump off the champs.

So how have the Wizards managed to surprise? In a word: defense. Washington was a mediocre defensive team last year, ranking 19th overall in Defensive Efficiency. (Defensive Efficiency measures how many points a team give up per 100 opponent possessions). The Wizards didn’t figure to be any better this year, since first-team All Defense selection Larry Hughes left for Cleveland. Moreover, the players Washington used to replace Hughes – Antonio Daniels, Caron Butler, and Chucky Atkins – never have been confused with Bill Russell defensively.

But the Wizards have not only survived Hughes’s loss, they’ve become better than ever on that side of the ball. Part of the reason is that Hughes’s defensive skills are grossly overrated. He led the league in steals a year ago, but his on-ball defense wasn’t particularly impressive, and when his gambles failed, they often left openings for opposing defenders to exploit.

The Wizards also have some capable holdovers, particularly center Brendan Haywood. An emerging defensive star who should get serious All-Defense consideration this season, Haywood has been the distracting interior presence every top-caliber defensive team needs. The 7-footer not only polices the middle, he also surprises opponents with his ability to switch out and defend smaller players when the need arises. The most notable example came in the season opener in Toronto, when Haywood switched onto the Raptors’ Jalen Rose on a key last-minute possession and drew a game-saving charge.

Cynics will point out that the Wizards’ early-season schedule hasn’t presented a slate of high-powered offenses. Of Washington’s first six opponents, only the Spurs are above the league average in Offensive Efficiency (the companion stat to Defensive Efficiency), and even they are just barely above.

Meanwhile, opponents like the Knicks, Magic, Raptors, and Sonics are well below the norm. Thus, Washington’s defensive stats may not sparkle this much once they’ve played the Dallases and Milwaukees of the world. But they still figure to make a huge improvement on a ranking of 19th,and are a major reason the Wizards can handle an opponent like San Antonio.

Besides, the improved defense means the Wizards can now show off what a talented offense they possess. Washington ranks third in the NBA in Offensive Effiency, and unlike the defense, that’s been accomplished against solid opposition. The Spurs are one of the all-time best defensive teams in basketball, while the Clippers, Knicks, and Magic all are above the league average, yet Washington has picked them apart.

The catalyst is Arenas, who may actually be benefiting from Hughes’s absence. With those two paired in the backcourt, the Wizards had a repetition of skills. Both excelled at taking opponents off the dribble, but neither was a good passer or outside shooter. As a result, opponents would sag in the lane and force both into contested shots.

With Hughes replaced by the likes of Daniels and Butler, Arenas has more room to operate, and he’s used it to stake his claim as the best point guard in the East. Through six games, his stats are MVP-caliber: 28.5 points a game on 50.8% shooting. He’s even doing well in areas that haven’t been strengths in the past, shooting 43.6% on 3-pointers and handing out six assists per game.

Butler is also making a huge impact, filling in the scoring void left by Hughes, but doing it while controlling the ball much less. The Wizards’ sixth man is averaging 17.8 points per contest and shooting 47.9%, helping to carry a second unit that was a weakness last season.

Two other bright spots are Antawn Jamison and Jarvis Hayes, each of whom have come back from knee troubles to average double figures. Jamison is pumping in over 20 a night and throwing in 9.5 rebounds – an important contribution for a team that overall is fairly poor on the glass. Hayes, meanwhile, missed the second half of last season but has returned better than ever, contributing strong defense in addition to his 10.2 points off the bench.

Add it all up, and the Wizards look like a legitimate threat to break into the upper crust of the Eastern conference. They may not have the Heat quaking in their boots just yet, especially if Shaq can stay in the lineup the rest of the way once he returns. But the Wizards’ impressive weekend seems to prove they’re a shoo-in for the playoffs, and provides yet another sign that the formerly weakling Eastern Conference is getting stronger by the day.

Mr. Hollinger is the author of the 2005-06 Pro Basketball Forecast.