WALTHAM, Mass. — While Rajon Rondo  spoke earlier in the day about the long-term security his new deal would provide, the Celtics waited till every detail was in place before announcing Monday night that they have re-signed their All-Star point guard to a contract extension, thus avoiding restricted free agency next summer.
WEEI.com’s Jeff Goodman confirmed through NBA sources that the extension is worth $55 million over five years.
The following was the release from the team:
The Boston Celtics  announced today that the club has signed point guard Rajon Rondo to a multi-year contract extension. Per team policy, terms of the deal were not disclosed.
‘We are extremely pleased to be able to extend Rajon’s contract,’ said Celtics President of Basketball Operations, Danny Ainge. ‘We believe that he is one of the elite point guards in the NBA and has a tremendous future ahead of him.’
Rondo, a 6’1’ guard, is currently leading the NBA in total assists (47) and is second in assists per game (11.8) through four games this season. The former Kentucky Wildcat is also leading the NBA in total steals (10). Last season, Rondo became the second Celtic to post three triple-doubles in a postseason joining Larry Bird  when he posted three during the 1985-86 postseason. During the 2009 postseason, Rondo just missed averaging a triple-double when he finished with an average of 16.9 points, 9.7 rebounds and 9.8 assists in 41.2 minutes per game.
‘I would like to thank the Celtics ownership, Danny Ainge, Doc Rivers , my teammates and the Celtics organization for all of their support over the years,’ said Rondo. ‘I would also like to thank my family, friends and fans. I’m ready to do everything I can to bring banner 18 to Boston.’
During his second season as a professional Rondo helped the Celtics win their 17th NBA Championship with averages of 10.2 points, 4.1 rebounds, 6.6 assists and 1.73 steals per game. Rondo became just the third starting point guard in the past 30 years to have won an NBA championship at the age of 22 or under joining Tony Parker  and Magic Johnson .
Rondo was named to the All-NBA Defensive Second Team after the 2008-09 season when he averaged 1.86 steals per game and finished fifth-best in the NBA in steals per game. The fourth-year pro finished with the fourth highest single season assist total in franchise history during the 2008-09 season (659). As a second year player in the 2007-08 season, Rondo was named to the Sophomore squad for the Rookie-Sophomore Challenge and Youth Jam in New Orleans during the 2008 NBA All-Star Weekend.
Since joining the Celtics in 2006, Rondo has increased his output each season with his points per game, rebounds per game and assists per game growing each year. Rondo achieved career-highs during the 2008-09 season in points (953), rebounds (416), assists (659), minutes (2,642) and steals (149). Rondo also achieved a career-high in field goal percentage last year (50.5%) which was good enough for 20th in the NBA and second among all guards in the NBA.