BOSTON – The deepest backcourt in the NBA just became even deeper, at least according to Boston Celtics head coach Doc Rivers.

The Celtics announced today that they have signed former Sixth Man of the Year Leandro Barbosa. Barbosa is a nine-year NBA veteran who owns career averages of 12.5 PPG, 2.2 RPG and 2.4 APG.

The 6-foot-3 guard from Brazil joins a backcourt crop that already boasts several dynamic talents. Rivers has preached to anyone who will listen that, when healthy, the Celtics’ backcourt group of Rajon Rondo, Jason Terry, Courtney Lee and Avery Bradley is the best in basketball. Barbosa now gives Rivers two former Sixth Man of the Year winters, along with Terry.

Much like Terry, Barbosa’s greatest skill is his ability to deliver points off the bench. He has established himself as an offensive sparkplug throughout his three stops in Phoenix, Toronto and Indiana. Barbosa’s best offensive season came back in 2006-07, when he averaged 18.1 PPG off the bench for the Suns en route to the Sixth Man of the Year award. He shot 47.6 percent from the field and 43.4 percent from 3-point range that season.

His numbers have dipped since that season but don’t let the raw numbers fool you: he can still get it done offensively. Barbosa’s statistical declines are due in large part to a decrease in playing time. His minutes per game average maxed out at 32.7 in 2006-07, but he has received less than 25.0 minutes of action in four of his five seasons since then.

To more accurately depict what his offensive numbers really mean, let’s take a look at what Barbosa provides on a per-36 minute basis. He averaged 19.9 points per 36 minutes back in his Sixth Man of the Year campaign and his numbers have been near that ever since. In 2008-09, he has a career-best average of 21.0 points per 36 minutes. In 42 games with Toronto last season, he scored 19.5 points per 36 minutes.

The raw data may indicate that Barbosa is sliding downward in his NBA career, but when playing time is taken into consideration it becomes clear that he can still score the basketball at a high rate. The speedy guard proved that last season with Toronto, and he continued to prove it as recently as this summer at the 2012 London Olympics.

Barbosa was impressive while assuming the role of starting shooting guard for the Brazilian national basketball team. He was the eighth-highest scorer in the tournament with 16.2 PPG while leading Brazil to a surprising fifth-place finish. Barbosa drilled 49 percent of his field goals and 40 percent of his 3s in six games.

The Gasol brothers and Jose Calderon can attest to how much Barbosa still has left in the proverbial tank. Barbosa scored 23 points during an 88-82 upset over Spain, including 10 clutch points in the final six minutes.

After those performances, one has to wonder how Barbosa remained on the free agent market for so long. He proved himself this summer and his per-36 minute averages have been consistent throughout his lengthy career. Sure, his shooting percentages have dipped slightly over the years, but he has made 46.1 percent of his field goals, 39.1 percent of his 3-pointers and 82.3 percent of his free throws over nine NBA seasons. As many shooting coaches would attest, once a shooter, always a shooter.

This shooter is now a member of the Boston Celtics and his addition makes the deepest backcourt in the league even deeper. Rivers might have a difficult time dishing out minutes to all of this talent, but we suspect he doesn’t have the slightest quarrel with that.