Rockets guard James Harden had spent the bulk of four seasons going against the best defenders and most carefully considered defenses put in his path.

He knows the best of NBA defense when he sees it. He has seen it lately without having to deal with the long and tenacious defender he was ready to declare among the league's best.

Harden does not have to go at teammate Trevor Ariza, but he had seen enough to lobby for a place for Ariza in the echelon of the league's best and to start the campaign for recognition that has eluded Ariza more than the vast array of scorers he faces.

"Trevor has been guarding the best player on each team every night," Harden said. "He's been doing an unbelievable job. He doesn't get the credit he deserves for defensive player of the year, first-team All-Defense. Unbelievable job by him."

Steals tell the story

As a defense-first player on a poor defensive team that allowed 125 points in Saturday's loss, Ariza is easy to overlook even as his burdens have increased. That could change. Though the best defense often is not found in traditional statistics, Ariza could be putting up numbers to get noticed.

He has had at least two steals in 15 consecutive games, the longest run in the NBA since Baron Davis did it in 18 consecutive games in the 2006-07 season. He has moved to second in total steals, one behind Russell Westbrook, and in a tie for second in steals per game, less than one-tenth behind Kyle Lowry.

He's done it while facing the most difficult defensive assignment the Rockets could find for him, keeping him attached to high scorers rather than roaming in search of steals.

"If you ask coaches, they'll tell you you prepare for him offensively when he's on the defensive end of the floor," Rockets interim coach J.B. Bickerstaff said. "Individuals when they play against him, they know he's coming and they do more to get ready for him. He's on their mind. And if you're the point guard and you're trying to enter the ball to your best player, you have to worry about Trevor getting in the passing lane and creating disruption there, too."

All that could make an argument for the honors Harden lobbied unsolicited for Ariza to receive.

"It would be real cool," Ariza said. "As long as we win, that's all that really matters. Individual rewards are nice, but team success matters most to me."

Perhaps no player has faced the variety of defensive challenges the Rockets have asked Ariza to take on, pitting him against everyone from the 6-11, 270-pound DeMarcus Cousins to the 5-9, 185-pound Isaiah Thomas. He has denied Anthony Davis touches, taken away Damian Lillard's shots and fronted Dirk Nowitzki from the low post to the elbow.

'The ability to do it'

Still, the Rockets' defensive struggles make it easy to overlook any individual's defensive efforts.

"There's not many guys who can do it in our league," Bickerstaff said. "It takes a combination of size, quickness, determination and intelligence.

"Trevor has the ability to do it. One game he's guarding Damian Lillard. A couple days later, he's guarding Anthony Davis and did a tremendous job on both of them. There may be three guys in the league - LeBron (James) is one and Trevor is another - that can do those types of things. Tony Allen was the third guy that comes in mind, but I haven't seen him guarding fours as much."

Those assignments require different skills, from the ability to rapidly circle around screens to chase jump shooters to slide in front of ball-handlers and battle for position to front low-post scorers.

But there is something each of his foes, with rare exceptions, have in common.

Staying locked in

"The people that I usually guard are the people who are going to have the ball in their hands," Ariza said. "I have to be locked in to them. That's not an easy task, but it does make you stay locked in, especially if you want to have an opportunity to win. Then, you also have to pay attention to your team defense."

Asked his toughest assignments, Ariza hesitated, as if not wanting to single out stars to the exclusion of others. That wasn't it.

He tried, starting with Cousins. Then he said James. He had to add Carmelo Anthony. Finally, he went with the assignment that defines his job.

"Everybody," Ariza said. "Everybody's tough. They're all different, but they're all very, very hard to defend."

There is one scorer he has not had to try to stop.

For that, Harden gave thanks.