In his first professional season, Dinkelman played for the Elizabethton Twins of the RookieAppalachian League. Over 46 games played, Dinkelman batted.298 with four home runs and 32 runs batted in. Defensively, Dinkelman predominately played as a second baseman. In 2007, he was selected to play in the Western Division of the Midwest League All-Star game, representing the Beloit Snappers. In June of the same year, he was promoted to the Advanced A classFort Myers Miracle; combined, Dinkelman batted.269 in 131 games played, and was voted the "Mightiest Miracle Player" by fans. In 2008, Dinkelman continued his professional career, playing for the Miracle as well as the New Britain Rock Cats. Along with teammates Rob Delaney, Jeff Manship, Anthony Slama and Danny Valencia, Dinkelman represented the Fort Myers Miracle in the Florida State League All-Star game. He finished the season with the AA Rock Cats, batting a combined.272 with four home runs, 40 RBI, and 12 stolen bases. From May 1–7, 2009, Dinkelman was the Twins' Minor League Player of the Week. He was named to his third consecutive All-Star team after batting.299 with four home runs and 43 RBI in the first half of the season. For the year, Dinkelman posted club highs in hits, doubles and walks to help the Rock Cats make their first post-season appearance since 2003. After the season, Dinkelman was named to the Eastern League All-Star Post-Season team as a utility player. Dinkelman spent the entire 2010 season with the Rochester Red Wings. He led his team in games played, total bases, and hits, while playing right field, left field and second base. He began the 2011 year with the Red Wings before being promoted to the Minnesota Twins on June 2, 2011, to replace shortstopTrevor Plouffe. On June 4, 2011, Dinkelman made his MLB debut, where he was hit by a pitch and intentionally walked, while also recording a single. He was to the Red Wings on June 16, and recalled to the Twins on September 5, 2011. For the Twins in 2011, Dinkelman batted.301, with four RBI and no home runs. However, he also had a.373 BABIP, contributing to his high average. On October 22, after being outrighted off the roster, he declared free agency. Later in the 2011 while with Rochester, Brian made a grab that was featured as number 1 on ESPN's SportsCenter top 10 plays. On November 10, 2011, Dinkelman signed a minor league contract to return to the Minnesota Twins. He played all of 2012 with Rochester, but he missed 2 months of the season from a hand injury. In 74 games, he hit.252 with 4 HR and 32 RBI. On October 29, 2012, Dinkelman re-signed with the Twins. Dinkelman once again played the season in Rochester, and was used mostly off the bench. In 84 games in 2013, he hit.215 with 6 HR and 23 RBI. Over 4 seasons and 427 games with Rochester in his career, he hit.248 with 21 HR and 150 RBI.