Roberts made his Major League debut in 2001 and played 75 games for Baltimore, batting .253.
He also played for the Bowie Baysox of the Class AA Eastern League and Rochester that year.

In 2002, he played 38 games with the Orioles and batted .227.
He stole 22 bases on 26 attempts.
He also played 78 games with the Orioles AAA affiliate in Rochester.

In 2003, he started for Ottawa, playing 44 games and hitting .315.
In late May he was called up for injured second baseman Jerry Hairston, Jr. He hit his first Major League grand slam in his second game (and his first in any sort of professional play) in the 9th inning against the Anaheim Angels to win that game.
He finished with a .270 average in 112 games and stole 23 bases on 29 attempts (tied for eighth in American League).

The Orioles season started spring training in 2004 with both Hairston and Roberts on the roster.
Hairston fractured his finger in spring training, however, and Roberts became the opening day starter.
After Hairston returned from the disabled list, he was moved to right field, leaving Roberts at second base.
In August, Roberts batted .347 with ten doubles in 107 at-bats.
During the second week of August, Roberts was named the American League Player of the Week for hitting .531 over a span of six games.
He finished 2004 with a .273 average, collecting 175 hits in 159 games.
He also hit 50 doubles, which led the American League and was third-best in the majors.
His 50 doubles also broke the Orioles single-season record for doubles (originally set by Cal Ripken, Jr.) and the single-season AL record for doubles by switch hitters.

Prior to the 2005 season, Hairston was traded to the Chicago Cubs (along with Oriole prospects Mike Fontenot and David Crouthers) for Sammy Sosa, thereby cementing Roberts's position as the Orioles' starting second baseman.
In 2005, Roberts led the AL in batting average for the first several months of the season.
In addition, he showed an increase in power; prior to the 2005 season, he had only 12 career home runs, but by late June, he had already outmatched that total.
Fans awarded Roberts explosive offensive first half by voting him the starting second baseman in the 2005 Major League Baseball All-Star Game.
It was Roberts' first appearance in the All-Star game.
As the season wore on, Roberts slumped and the Orioles slipped in the standings.

On September 20, 2005, Roberts dislocated his elbow in a game against the New York Yankees.
The injury occurred in a collision with New York's Bubba Crosby at first base in the bottom of the second inning.
The injury prevented Roberts from playing the rest of the season.
Roberts made his Major League debut in 2001 and played 75 games for Baltimore, batting .253. He also played for the Bowie Baysox of the Class AA Eastern League and Rochester that year.
In 2002, he played 38 games with the Orioles and batted .227. He stole 22 bases on 26 attempts. He also played 78 games with the Orioles AAA affiliate in Rochester.
In 2003, he started for Ottawa, playing 44 games and hitting .315. In late May he was called up for injured second baseman Jerry Hairston, Jr. He hit his first Major League grand slam in his second game (and his first in any sort of professional play) in the 9th inning against the Anaheim Angels to win that game. He finished with a .270 average in 112 games and stole 23 bases on 29 attempts (tied for eighth in American League).
The Orioles season started spring training in 2004 with both Hairston and Roberts on the roster. Hairston fractured his finger in spring training, however, and Roberts became the opening day starter. After Hairston returned from the disabled list, he was moved to right field, leaving Roberts at second base. In August, Roberts batted .347 with ten doubles in 107 at-bats. During the second week of August, Roberts was named the American League Player of the Week for hitting .531 over a span of six games. He finished 2004 with a .273 average, collecting 175 hits in 159 games. He also hit 50 doubles, which led the American League and was third-best in the majors. His 50 doubles also broke the Orioles single-season record for doubles (originally set by Cal Ripken, Jr.) and the single-season AL record for doubles by switch hitters.
Prior to the 2005 season, Hairston was traded to the Chicago Cubs (along with Oriole prospects Mike Fontenot and David Crouthers) for Sammy Sosa, thereby cementing Roberts's position as the Orioles' starting second baseman. In 2005, Roberts led the AL in batting average for the first several months of the season. In addition, he showed an increase in power; prior to the 2005 season, he had only 12 career home runs, but by late June, he had already outmatched that total. Fans awarded Roberts explosive offensive first half by voting him the starting second baseman in the 2005 Major League Baseball All-Star Game. It was Roberts' first appearance in the All-Star game. As the season wore on, Roberts slumped and the Orioles slipped in the standings.
On September 20, 2005, Roberts dislocated his elbow in a game against the New York Yankees. The injury occurred in a collision with New York's Bubba Crosby at first base in the bottom of the second inning. The injury prevented Roberts from playing the rest of the season.
Brian Roberts (baseball)