From BR Bullpen
Guillermo Alejandro Moscoso
- Bats Right, Throws Right
- Height 6' 1", Weight 165 lb.
- High School Liceo Jose Luis Ramos
- Debut May 30, 2009
 Biographical Information
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.
On September 7, 2011, pitching for the Oakland Athletics, 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.