Quintanilla attended the University of Texas at Austin on a baseball scholarship. He played second & third for the Longhorns, appearing in two National Championship games. He became the first round pick of the Oakland Athletics in 2003 (the 33rd pick overall).
While still a hot prospect he was traded along with Eric Byrnes to the Colorado Rockies in exchange for Joe Kennedy & Jay Witacisk. Quintanilla spent five years with the Rockies as a backup middle infielder, playing behind Troy Tulowitzki, Kazo Matsui & Clint Barnes.
He saw the most action in 2008, batting .238 with 17 doubles, two HRs & 15 RBIs. He was part of the 2007 NL Champion Rockies season, playing 27 games. He was with the club in April May & September but did not play in the post season.
In 2010 he received a 50 game suspension by MLB for using a performance enhancing drug. The solid infielder signed with the Texas Rangers in 2011 seeing action in just 11 games at the big league level for the AL Champion Rangers.
In 2012 he signed with the New York Mets, and played at 48 games with AAA Buffalo, hitting an impressive .333. He was called up to the Mets in May debuting on May 29th at Citi Field. Quintanilla had a huge day, with three hits & a pair of doubles in a 6-3 win over the Philadelphia Phillies. He began to see regular action filling in at shortstop & was batting over .300 until md June. On June 9th he hit his only HR of the season, it came off the AL New York's Phil Hughes.
In 29 games he hit his career best .257 with one HR & Four RBIs. In July he was traded to the first place Baltimore Orioles, to help out defensively for the playoff run.
The deal was for the Mets to have future considerations. He was granted free agency by Baltimore & got resigned by the Mets for 2013.
When Ruben Tejada went down with injury, Quintanilla was called up joining the club in time for the subway series sweep in New York. On June 2nd, at Marlins Stadium he hit his seventh career HR, it came at the start of a nine game hit streak, that saw him hit two doubles, two HRs & drive in three runs. He ended the streak batting .325 & with a HR against the Cardinals in a 9-2 loss at Citi Field.
In 2013 he saw action in 95 games (92 at short) posting a .978 fielding %. Overall he hit just .222 with 2 HRs 21 RBIs but did draw 38 walks.
Defensively Quintanilla's smooth play at short, impressed everyone, posting a .977 fielding% turning 44 double plays. In 2014 he played just 15 games at the big league level batting .207. He played 46 games for AAA Las Vegas & was designated for assignment in early summer.In a nine year career he has played in402 games, batting .207 with 228 hits, 43 doubles, 5 triples 8 HRs & 74 RBIs. He has posted a .981 fielding % in 229 games at short stop. He has also played 140 games at second base & 14 games at third.