[5] He struggled tremendously while adjusting to his new team, namely in an incident at Real Betis on 27 September 2009 (0–0 draw) where he was subjected to constant racist abuse by the opposing fans.

[14] Eleven months later, he was loaned to San Jose Earthquakes of Major League Soccer,[15] scoring two of their three goals on 12 May in the 3–1 home victory over Houston Dynamo FC.

[17] He was initially criticized by the team's supporters for not being fit for playing; however, after the arrival of manager Pedro Troglio, Quintero became one of the club's players who stood out the most, scoring a career-best 13 goals in his first season.

[22] In May 2018, Quintero was named in Panama's final 23-man squad for the upcoming edition of the FIFA World Cup in Russia.

[23] On 6 June, however, he suffered a fractured foot in a friendly with Norway after a collision with Bjørn Johnsen, thus being ruled out of the tournament and replaced by Ricardo Ávila.