Barton was drafted by the St. Louis Cardinals in the 2003 Major League Baseball Draft in the 1st round as the 28th overall player selected. He was selected right out of Marina High School in Huntington Beach, California. Barton had signed on to attend Cal State Fullerton and play baseball there, but accepted a one million dollar signing bonus from the Cardinals instead.
Minor league careerEdit
In 2004, he advanced to the Peoria Chiefs, the Cardinals Single-A team. He played in just 90 games for the Chiefs, batting .313 with 13 home runs. He was named to the Midwest League Postseason All-Star team. He led the Midwest League in on-base percentage (.445), was third in the league in batting average (.313), and was fourth in the league in slugging percentage (.511).
Barton was #32 out of 100 on Baseball America's Top 100 Prospects list in 2005. After having an emergency appendectomy part way through spring training, Barton started the 2005 season slowly, but ended the year with a .317 batting average. He spent most of 2005 with the Single-A Stockton Ports of the California League, but also appeared in 56 games for the Double-A Midland RockHounds of the Texas League. He was also selected to play in the All-Star Futures Game at PNC Park in Pittsburgh. With the Cardinals, Barton played catcher, but the Athletics moved Barton to first base due to concerns with Barton's ability behind the plate, the negative impact catching can have on the development of a young hitter, and because the Athletics had a number of more advanced catching prospects (Kurt Suzuki and Landon Powell).
In 2006, Barton once again appeared on Baseball America's Top 100 Prospects list, this time ranking at #28. He was also ranked as the Athletics #1 prospect. He played for the Triple-A Sacramento River Cats in 2006, but due to injuries, played in only 43 games. He batted just .259 with 2 home runs in those 43 games.
In 2007, Barton appeared on Baseball America's Top 100 Prospects list, this time ranked at just #67. He was ranked as the Athletics #2 prospect behind outfielder Travis Buck, who ranked at #50 on the Top 100 Prospects list. Barton began the 2007 season slowly with the Sacramento River Cats, hitting just .221 in April and .273 in May. He finally got started in June when he hit .454 in 27 games. He was named to the Pacific Coast League Mid-Season All-Star team on July 11. He finished the 2007 minor league season with a .293 batting average and 9 home runs in 137 games.
Following the 2007 minor league season, the River Cats advanced to the first round of the playoffs. They played the Salt Lake Bees, the Angels Triple-A affiliate. In the first round, Barton batted .550 (11-20) with 10 RBI. He had a power surge with 4 home runs and one of the home runs was a decisive one in Game 5 as it led the River Cats into the second round of the playoffs. He did not join the team for the second round as he had his contract purchased by the Athletics major league club on September 10.  He wasn't expected to get called up until the River Cats season was over.
Major league careerEdit
Barton made his major league debut on September 10, 2007, against the Seattle Mariners. In his first two plate appearances, he walked both times. In his third plate appearance, he had his first major league hit off Ryan Feierabend, which was a double.
Barton ended up playing in 18 games for the Athletics in 2007. He reached base safely in all 18 games via a hit or a walk. In those 18 games played, he hit .347 (25-72) with 4 home runs and 8 RBI.
In 2008, Barton was the Athletics' starting first baseman. He batted just .226 with 9 home runs and 47 RBI in 140 games. During the All-Star break, Barton dove into a shallow pool and hit his head on the bottom. He suffered a jammed neck and had to get staples to close a cut on his head, but did not suffer any paralysis.
On April 5, 2009, the day before the A's season opener, Barton was demoted to Triple-A Sacramento. 
Barton is a hitter who hits for average and is known to be a patient hitter who hits for a high on-base percentage and walks more than he strikes out. In 5 minor league seasons, he had 313 walks as opposed to 266 strikeouts.
- ↑ Urban, Mychael. "Notes: Barton called up to see action", MLB.com, September 10, 2007. Accessed September 13, 2007.
- ↑ Smith, Matt. "Notes: Geren reflects on first season", MLB.com, September 30, 2007. Accessed October 1, 2007.
- ↑ "Notes: Oakland's Barton jams neck after dive into shallow pool", Yahoo.com, July 20, 2008. Accessed October 7, 2008.
- ↑