Keeping Score: For Thunder, Martin Is a Definite Plus One of the more shocking developments in the days leading up to the start of the 2012-13 season was the trade of James Harden to the Houston Rockets from the Oklahoma City Thunder. The loss of Harden, the reigning sixth man of the year and a member of the United States Olympic team, was expected to have a negative effect -- both in the short term and the long term -- on the Thunder. But Kevin Martin, acquired by Oklahoma City from Houston in the trade, has done a fantastic job filling Harden's shoes, and by some measures Martin has outplayed the man he replaced. Martin struggled with the Rockets in 2011-12, as he missed 42 games because of injury and had the second-worst shooting season of his career. But in the five seasons before that, Martin had been one of the most efficient scorers in the N.B.A. True shooting percentage is a measure of scoring efficiency that takes into account 2-point field goals, 3-point field goals and free throws. From 2006-7 through 2010-11, Martin's true shooting percentage of 60.1 percent was the third best in the league among guards with at least 200 games played. After posting a true shooting percentage of 55.4 percent last season -- a subpar performance for Martin but still better than the league average -- Martin's hyperefficient scoring has returned. He currently leads the league with a true shooting percentage of 70.3 percent, a mark that is outpacing Harden's figure of 66.0 percent from last season. Like Harden's, Martin's scoring efficiency is a product of his steady 3-point shooting and his ability to draw fouls and convert from the free-throw line. Martin has hit 53.6 percent of his 3-point attempts this season, making him the league's sixth-best marksman from long range. For his career, Martin has hit 38.1 percent of his shots from downtown, well above the break-even point of 30.4 percent (since 2004-5). Martin averages 50.4 free-throw attempts for every 100 field-goal attempts, a rate that is good for eighth in the league among players with at least 250 minutes played. Harden is one spot ahead of Martin with a rate of 51.0. And Martin has cashed in on those attempts, making 94.7 percent of his free throws, the second-best percentage in the N.B.A. One thing to keep in mind is that it is still early in the season, and it is unlikely that Martin will continue to shoot at his current clip. But the good news for Thunder fans is that even if Martin regresses toward his career norms, he will still be one of the most efficient scoring guards in the league. Harden grabbed the headlines by scoring 37 and 45 points in his first two games with Houston, but Martin has been a steady force off the bench for Oklahoma City. Although it is much too early to make any sweeping judgments, thus far the trade has worked out just fine for the Thunder. All statistics through games of Nov. 20.