The answer? Kevin Durant, one of the league's toughest players to shut down.
In 2012-13, the Oklahoma City Thunder superstar posted one of the greatest shooting seasons in NBA history. He became one of only seven players ever to have averaged more than 10 points per game while shooting at least 50 percent from the field, 40 percent from three-point range and 90 percent from the free-throw line, according to Basketball-Reference.com.
If not for a late-season scoring surge from Carmelo Anthony, K.D. would have become the first scoring champion in league history to post a 50-40-90 season.
That shooting proficiency makes Durant lethal from the second he steps across the half-court line. He's only growing as a passer, too, as evidenced by his career-high 4.6 assists per game during the 2012-13 season.
Does that make Durant the toughest cover in the NBA today? To answer that question, let's see how he stacks up compared to the best shooter in the league, Stephen Curry, and the two-time reigning MVP, LeBron James.
Durant vs. Curry
Four years into his career, Curry may be the NBA's most terrifying sharpshooter.
In each of his four seasons, he's knocked down at least 50 three-point field goals while shooting 43.7 percent or better from long range. Only 19 players have accomplished that feat even once in the past four years, according to Basketball-Reference.com—Curry is the only one to do it more than twice.
During the 2012-13 season, Curry drilled 272 three-pointers, breaking Ray Allen's all-time record for most threes made in one year. Incredibly, he shot over 45 percent from long range in 2012-13 despite attempting nearly eight threes per game.
In terms of long-range shooting alone, Curry holds a clear edge over Durant. The Oklahoma City star has only cracked the 40-percent mark from downtown twice in his six NBA seasons.
Three-point shooting isn't the only factor we should consider when comparing the two stars, though.
Below, I've pulled Synergy Sports data for both players from the 2012-13 season. The first number in each cell represents the points per possession (PPP) generated on the specific play type, and the second denotes where that mark ranked among NBA peers.
While Curry may hold the edge in terms of three-point shooting, K.D.'s overall offensive efficiency during the 2012-13 season trumped that of his diminutive counterpart.
In particular, Durant's advantages in isolations, cuts and transition more than offset Curry's edge in spot-up and off-screen shot attempts. The Oklahoma City Thunder star ranked among the NBA's top 25 in five of the seven possession types featured here—Curry only cracked the top 25 in spot-ups and coming off screens.
One look at both players' respective shooting percentages confirms what the Synergy data suggest. Curry converted a career-low 45.1 percent of his total shot attempts in 2012-13, while Durant finished the year with a career-high shooting percentage of .510.
In short: Curry's long-distance aptitude isn't enough to tip the overall scales in his favor compared to Durant. Once you consider their possession-by-possession statistics from 2012 and their overall shooting percentages, it's a landslide in favor of K.D.
With that settled, let's turn our attention to the main entree: James, the two-time reigning MVP, versus Durant, the runner-up for the past two seasons.
Durant vs. LeBron
Kobe Bryant and Carmelo Anthony deserve an ancillary mention in the "toughest-to-cover" conversation, but ultimately, it boils down to a choice between James and Durant.
Both players excel at destroying defenders in a multitude of ways. Durant prefers coming off screens to pepper opponents with mid- and long-range jumpers, while James does far more of his damage in transition.
Looking at their head-to-head possession data from the 2012-13 season only amplifies those differences:
K.D. logged nearly four times as many shots coming off screens (240) than LeBron did (64) in 2012-13, according to Synergy Sports. Off-screen possessions comprised nearly one-eighth of Durant's total touches, while they represented only 3.2 percent of LeBron's.
Durant held the edge over LeBron in terms of field-goal efficiency coming off screens, too. James knocked down 27 of his 64 shot attempts off screens in 2012-13, or 42.4 percent, while Durant drained 109 of his 240 attempts (45.4 percent).
Conversely, James held a major edge over Durant in terms of transition efficiency. LeBron converted nearly 76 percent of his 299 transition shots throughout 2012-13, while Durant only knocked down 61.6 percent of his 203 transition field-goal attempts.
That discrepancy translated into almost a 0.2 PPP advantage for King James over K.D. in terms of transition buckets.
Surprisingly, LeBron finished the season with a better field-goal percentage and a higher PPP in spot-up opportunities. Despite Durant registering nearly 55 more spot-up field-goal attempts than James during the 2012-13 season, LBJ only trailed K.D. by 14 made spot-up shots.
Both players posted frighteningly similar numbers in terms of overall possessions (2,368 for Durant, 2,388 for LeBron) and isolation possessions (562 and 567, respectively). LBJ notched 79 more plays as the ball-handler in pick-and-rolls, while Durant served as the roll man in pick-and-rolls nearly twice as often as the Miami Heat star (93 vs. 49).
The moral of the story? Both LeBron and Durant sliced and diced defenses in a plethora of ways throughout the 2012-13 season.
But in terms of the single toughest cover in the NBA...
The Verdict: Long Live the King
For the time being, there's no tougher cover in the NBA than James.
His ability to dissect defenses is unparalleled now that he's finally developed a working post game. His massive frame (he's listed on NBA.com as 6'8" and 250 pounds) allows him to bully smaller defenders in the paint, but he's also proven more than capable of drilling clutch jumpers when necessary.
When you add in his ability to break down double-teams by passing to open teammates, he's become virtually unstoppable.
Durant holds the title of the NBA's most efficient scorer, as evidenced by his 50-40-90 season in 2012-13, but James earns the "toughest-cover" honors for now.
Don't be surprised to see the two flip-flop in coming seasons, however. If Durant continues to improve upon his passing ability and stays dedicated to avoiding "rotten-apple" shot attempts, the sky is the limit for the young Oklahoma City superstar.
He doesn't even turn 25 until September 29, after all.