When LeBron James bitterly walked away from the final game of the Cavaliers' season in June, he did it with a firm promise that he would spend this summer devoted to improving his game.

How that would be possible was unclear.

James needed rest after the longest season of his career. His personal life included the birth of his second son, Bryce Maximus, and a commitment to host the ESPY Awards and a Saturday Night Live episode. In addition, he committed to play for Team USA in the FIBA Americas Championship.

Results on the court in that tournament in Las Vegas in the past two weeks have shown James is backing up the talk. In the past two months, he has been working diligently on improving his jumper with Cavs assistant coach Chris Jent. It's showing, as he has helped the Americans thrash the competition on Team USA's way to securing a berth in next summer's Olympics.

Heading into a game late Thursday night against Argentina, James was shooting better than any other player in the tournament. After shooting an incredible 11-of-11 and scoring 26 points in just the first half against Uruguay on Wednesday, James was making 80 percent of his shots and 70 percent (14-of-20) of his 3-point attempts.

In the first seven games in the event, he averaged 16.6 points, 3.3 rebounds and 4.3 assists, and also led the team in steals. He has also impressed Team USA's coaches by showing up to work on his shooting on scheduled days off.

''I've been focused on the jumper,'' James told reporters in Las Vegas. ''All I've been working on all summer is getting my jump shot better.''

In the NBA Finals, the San Antonio Spurs allowed James to take mid- and long-range jumpers and blocked his path to the basket. He shot just 36 percent, highlighting a weakness in his game that he saw as plainly as anyone else.

After changing his jump shot and free-throw shooting form numerous times in his four-year career, James has put hours in around his summer commitments and vacations to become more consistent.

He also has benefited from playing with a loaded Team USA and its new point-guard corps of Jason Kidd, Chauncey Billups and Deron Williams. The upgraded talent around him and the shorter 3-point line in international play have no doubt contributed to his success, but James' shooting has still been the story of the summer.

''It's a great sign for our team that he's showing so much focus during the summer, when he could be off on vacation and nobody would blame him,'' said Cavs assistant coach Mike Malone, who has watched James closely all summer because he's an assistant on the Canadian national team that is also competing in Vegas.

''He got a taste of it last season, and he is showing that he is going to come back hungry.''

James, who has played small forward and power forward for Team USA coach Mike Krzyzewski, has told people that he is now nearly 260 pounds. That's about 20 pounds heavier than his rookie season and around 10 pounds heavier than at the start of last season. Along with developing his jumper, James has been encouraged by Cavs coaches to become more confident in his post play, where the extra weight could help.

After hinting late in the season that he might need to take this summer off, James said he was influenced to play by friend and teammate Carmelo Anthony, who called him several times to plead. That, and the desire to be a major member of the team next summer, persuaded James to play, and it has paid off.

''It came down to my friends wanting me to be here,'' James said. ''Having fun with my friends and getting better are the reasons I decided I needed to be a part of the team.''

Dribbles

League sources said the Cavs have expressed interest in 16-year veteran center Dikembe Mutombo. He has been offered a contract to stay with the Houston Rockets but has not signed while he considers options. Most think that he is likely to stay in Houston. . . . After having conversations, the Cavs might look to bring in guard Allan Houston, who is coming out of retirement, for a workout next month. . . . Second-year guard Shannon Brown was not impressive in summer league in Las Vegas, but sources said he played very well in Tim Grgurich's camp in Vegas this month. He is expected to challenge for playing time in training camp.