Guillermo Alejandro Moscoso
- Bats Right, Throws Right
- Height 6' 1", Weight 165 lb.
- High School Liceo Jose Luis Ramos
- Debut May 30, 2009
Moscoso was signed by scout Ramon Pena for the Detroit Tigers in 2003. He went 2-0 with a 1.85 ERA for the DSL Tigers that summer, with 29 hits, 7 walks and 44 strikeouts in 39 innings. In 2004, he was 6-3 with two saves and a 1.90 ERA for the team, allowing 58 hits and 16 walks in 90 innings while striking out 102 and tying for second in the Dominican Summer League in complete games (3). With the 2005 Oneonta Tigers, the Venezuelan was 2-2 with a 4.37 ERA in 11 games.
He was 3-2 with a 2.50 ERA for the 2006 GCL Tigers, walking 8 and fanning 33 in 36 innings. In 2007, Moscoso pitched three scoreless innings for the Lakeland Tigers in June then returned in July with Oneonta. He began 3-0 with a 1.78 ERA in his first five starts. The fifth was the historic one, a perfect game against the Batavia Muckdogs on July 15. He had not allowed an earned run in 20 2/3 IP over his last three starts at that point. It was the first perfecto in the New York-Penn since Gregory Diehl in 1974 and the first nine-inning perfect game since John Herbert in 1956. He had a 8-2, 2.37 record for Oneonta and had a 68:15 K:BB ratio in 79 2/3 IP. He only allowed one run in 8 innings for the West Michigan Whitecaps. He tied Drew Naylor and Adrian Alaniz for second in the New York-Penn League in wins, one below Dylan Owen. He tied Naylor for the league lead with 2 complete games and also tied for the lead with one shutout. He was 4th in ERA. Baseball America did not rank him among the circuit's top 20 prospects despite his success.
Moscoso split 2008 between Lakeland (2-3, Sv, 36 H, 72 K, 2.42 in 52 IP) and Erie SeaWolves (3-1, 24 H, 8 BB, 50 K in 34 2/3 IP, 3.12). Following the season, Detroit traded him with Carlos Melo to the Texas Rangers for Gerald Laird.
Moscoso began 2009 with the Frisco RoughRiders and was 3-1 with a 4.46 ERA after 9 games. Despite that indifferent work record, he was called up to replace Tommy Hunter on the Texas staff. He had an easy introduction to the majors, entering with a 14-1 lead in the 9th against the A's, relieving Warner Madrigal. Guillermo allowed a leadoff single to Jason Giambi, then struck out Landon Powell. Ryan Sweeney singled then Aaron Cunningham ground into a game-ending double play. He had a 3.21 ERA in 10 relief outings for the Rangers that summer and was 5-4 with a 2.31 ERA for the Oklahoma City RedHawks in addition to his opening-season work with Frisco.
He was 2-1 with a 3.38 ERA that winter for the Leones del Caracas. In the 2010 Caribbean Series, he allowed six hits, two walks and five runs (three earned) in 3 2/3 innings in dropping the opener to the Naranjeros de Hermosillo, his lone appearance of the Series. That summer, he fell to 7-7, 5.18 for Oklahoma City and struggled in his lone game for the 2010 Rangers (2 H, 2 BB, 2 R in 2/3 IP). He was 3-0 with a 2.66 ERA for Caracas in 2010-2011. Texas dealt him to the Oakland Athletics for Ryan Kelly.
He was 3-3 with a 3.88 ERA for the Sacramento RiverCats to open 2011. On September 7, 2011, Moscoso flirted with a no-hitter, keeping the Kansas City Royals off the hit sheet until two outs in the 8th. Salvador Perez hit a single, and Alex Gordon also recorded a hit in the 9th, and he ended up one out shy of completing a 7-0 shutout. The win capped a great season when he only joined the starting rotation in mid-year, when a number of A's hurlers went down with injuries, after a poor year pitching with the Oklahoma City 89ers in 2010. He stepped into the breach, though, and the win over the Royals brought his record on the season to 8-8. He finished 8-10 with a 3.38 ERA (119 ERA+). Only Gio Gonzalez and Brandon McCarthy had better ERAs among the A's regular starters.
Oakland packaged him with Josh Outman in a deal to the Colorado Rockies for Seth Smith, his third trade in four years. He had a lousy 2012 after his strong 2011, struggling both with the Rockies (3-2, 6.12 in 23 G) and the Colorado Springs Sky Sox (8-6, 6.13). One rare positive was his first MLB hit, a single off Dillon Gee of the New York Mets to score Michael Cuddyer. He was 2-1 with 3 saves and a 3.10 ERA for Caracas in the winter after a year away from Venezuela to bounce back from a poor summer, though he was 0-2 with a 6.05 ERA in the playoffs.
He then really bounced around. Before the 2013 season, the Rockies waived him and he was claimed by the Kansas City Royals. In spring training, the Royals waived him and the Toronto Blue Jays picked him. 11 days later, the Blue Jays waived him and the Chicago Cubs claimed his rights. He did well with the Iowa Cubs (7-5, 3.93, 94 K in 94 IP, though with 47 BB). The San Francisco Giants purchased his contract from the Cubs, his 7th organization. He went 2-2 with a 5.10 ERA in 13 games for the 2013 Giants, striking out 31 and allowing 20 hits but walking 21 in 30 innings. He was 3-3 with a 3.96 ERA for Caracas in the winter.
A free agent, he signed with the Yokohama BayStars for 2014. He pitched well in his Nippon Pro Baseball debut (4 H, 2 BB, 4 K in 6 IP) but lost a duel to Kenta Maeda, the ace of the Hiroshima Carp, 1-0. The only run came in the 3rd on hits by Yoshiyuki Ishihara, Yoshihiro Maru and Ryosuke Kikuchi and an error by Tony Blanco. Kentaro Takasaki relieved Moscoso.