Today we'll go back and look at left-handed reliever Al Osuna. Al was the Astros 16th round pick in the 1987 draft and in 1990 he made the jump from the AA Columbus MudCats to Houston. He converted a few save opportunities in 1991, then spent the next two seasons in Houston as middle reliever with an unusual reverse platoon split as he had more success against right-handed hitters than lefties.
Over the span of his Houston days Al was, on the whole, a below average pitcher. He appeared in 193 games and 180 innings, putting up a 3.75 ERA with 132 strikeouts and 103 walks. While that ERA may not look bad by today's standards, in the early 90's it only equates to a 94 ERA+. If Al had ever managed to get those walks under control he would have been much better for us.
While he was mediocre on average, he oscillated between good seasons and bad seasons. His final season in Houston was his best, as he appeared in 44 games and just 25.1 innings. It was that strong reverse split that led to this success, as he held opposing right-handed batters to a .452 OPS that season. He finished the year with a 3.20 ERA and 21 strikeouts against 13 walks.
Al's best game with the Astros is arguable, but we'll go with his appearance on June 16, 1991 against the Mets. Al was called upon to pitch in the bottom of the 8th with the Astros leading 5-4. The Mets went three up, three down in the 8th as the Astros clung to their lead. Osuna came back out to pitch the ninth and, after a leadoff single to Rick Cerone, retired the next three batters to earn a two inning save, ending the game when Daryl Boston stuck out looking.
Before the 1994 season Al was traded to the Dodgers for prospect Jimmy Daspit, who never appeared in the majors.
An interesting non-Astros related note, Al appears to have become a right-handed pitcher for his final season with the Padres in 1996. Details and/or verification of this unusual change are difficult to find, so if any readers have more information please comment.
Edit* The 1996 RHP listing may be a mis-classification. Baseball Almanac lists him as a LHP, Baseball-Reference lists him as a RHP. I'll keep digging.
Edit #2* I've verified with long time Padres blogger and current Baseball Prospectus writer Geoff Young that the RHP listing is indeed a typo by Baseball-Reference. Al Osuna was a still a LHP in 1996. On a side note, that's probably the most research anyone's done on Al Osuna in 15 plus years.