The Los Angeles Dodgers selected Valentín in the first round of the 2012 MLB Draft (51st overall) out of the Puerto Rico Baseball Academy[1] and he signed, forgoing his commitment to play college baseball at LSU.[2] The Dodgers assigned him to the Arizona League Dodgers to begin his professional career that year and he hit .211 with two home runs and 18 RBIs in 43 games. He split 2013 between the Great Lakes Loons and the Ogden Raptors, and he hit .264 with four home runs and 29 RBIs in 95 games. He began 2014 with Great Lakes where he hit .280 with seven home runs and 47 RBIs in 108 games.[3]
On April 11, 2015, he was placed on the restricted list and suspended indefinitely following his arrest for a domestic violence incident.[4] The Phillies added him to their 40-man roster after the 2016 season.[5] After he was activated off the restricted list, he returned to Clearwater, where he spent the whole season, posting a .273 batting average with one home run and 14 RBIs in 31 games. In 2016, he spent time with both the Reading Fightin Phils and the Lehigh Valley IronPigs, batting .269 with nine home runs, 52 RBIs and a .736 OPS in 125 combined games between both teams. He spent 2017 with Lehigh Valley where he batted .229 in 29 games[6] before a separated shoulder caused him to miss the remainder of the season.[7] He began 2018 with Lehigh Valley.
Major leagues
Valentín was promoted to the majors for the first time on April 29, 2018.[8] He recorded his first career Major League hit on May 7 against the San Francisco Giants.[9] He hit his first career home run and recorded his first multi-hit game on June 13 against the Colorado Rockies.[10] Valentín made an appearance as a pitcher in during a June 15 game against the Milwaukee Brewers, surrendering three runs over one inning while recording one strikeout.[11] He was designated for assignment on September 1. Valentín elected free agency following the season on November 2.[12]
Baltimore Orioles
On April 11, 2019, Valentín signed with the High Point Rockers of the Atlantic League of Professional Baseball. The next day, his contract was purchased by the Baltimore Orioles organization.[13] In 115 games for the Double–A Bowie Baysox, he hit .256/.334/.390 with 8 home runs, 46 RBI, and 10 stolen bases.[14] Valentín did not play in a game in 2020 due to the cancellation of the minor league season because of the COVID-19 pandemic.[15] He became a free agent following the season on November 2, 2020.[16]
Québec Capitales
On August 24, 2023, Valentín signed with the Québec Capitales of the Frontier League.[17] In 9 games he hit .323/.417/.387 with 0 home runs and 5 RBIs.
On November 21, 2023, Valentín re-signed with the Capitales.[18] In 65 games for Québec, he slashed .271/.383/.442 with nine home runs, 49 RBI, and nine stolen bases.