This story appears in ESPN The Magazine's Jan. 5 Championship Drive Issue. Subscribe today!

So what the heck is going on with James Harden?

You've seen the GIFs, the YouTube clips, the Twitter LOLs. We all know it: Harden stinks at defense. But this season, believe it or not, the Rockets' shooting guard leads the league in defensive win shares, meaning he's contributed more wins on D than any other NBA player. Whaaa? Our thoughts exactly. Let us seek metric enlightenment ...

Defensive Rating

Harden Career: 106

Harden 2014-15: 99

Defensive Win Shares

Harden Career: 2.4

Harden 2014-15: 5.9 (Projected)

Steals Per 100 Possessions

Harden Career: 2.1

Harden 2014-15: 2.6

THEORY 1: It's the X's and O's

Regardless of whether Harden's improvement is cause or effect, there's no question the Rockets are far better on defense: After ranking 13th in points allowed per 100 possessions last season (106.3), Houston ranks second this season (100.6). A main reason? "We've changed how we pressure off the ball," says GM Daryl Morey. "'No middle' is the primary focus -- shading all drives to the baseline toward the bigs." The result: Houston allows just 46.6 percent of opponents' shots to come from within 10 feet, down from 54.3 percent last season, and is holding foes to 29.3 percent from 3-point range, second-lowest in the league.

Points Allowed Per 100 Poss.

Rockets 2013-14: 106.3

Rockets 2014-15: 100.6

Opponent 3PT Percentage

Rockets 2013-14: 35.3

Rockets 2014-15: 29.3

THEORY 2: It's the team, mates

Schemes, of course, work only as well as the players who execute them, and the Rockets added perfect complementary pieces to their perimeter D. Exhibit A: Trevor Ariza. "Ariza's presence and the absence of Jeremy Lin really help," says an Eastern Conference executive. Ariza, who replaced Chandler Parsons at small forward, immediately gave the team a perimeter stopper; Lin, who had a paltry 109 defensive rating last season, was sent to the Lakers in the offseason. And Patrick Beverley, as the starter at point, has only added to his lockdown rep this season -- with a defensive RPM* of plus-0.66, ninth best among PGs.

Points Allowed Per 100 Poss.

2013-14 James Harden, Jeremy Lin, Chandler Parsons: 105.1

2014-15 James Harden, Patrick Beverley, Trevor Ariza: 98.8

Opponent eFG Percentage**

2013-14 James Harden, Jeremy Lin, Chandler Parsons: 50.0

2014-15 James Harden, Patrick Beverley, Trevor Ariza: 46.3

THEORY 3: Harden is trying harder

Harden's deficiencies on D have long seemed more a matter of effort than skill, and the defensive focus he discovered this past summer for Team USA seems to have carried over to this NBA season. "You don't see him take as many plays off at that end," says a Western Conference assistant coach. Last season Harden was in the 11th percentile on isolation plays (1.07 ppp allowed), according to Synergy Sports. This season? He's in the 66th -- a transformation from abysmal to average that has done wonders for the team's D. Harden is not worthy of the all-defensive team just yet, but he no longer belongs on Vines.

Overall Defense (Percentile)

Harden 2013-14: 65th

Harden 2014-15: 82nd

Isolations (Percentile)

Harden 2013-14 : 11th

Harden 2014-15: 66th

All stats through Dec. 19

*Real Plus-Minus uses play-by-play data to determine each player's impact on each possession.

**Effective FG Percentage adjusts for the fact that 3-pointers are more valuable than 2-pointers.