Plucked from the Toronto Blue Jays system in the, 1989, Rule 5 draft, Xavier Hernandez would spend the next four years pitching with varying degrees of success in Houston.
His pitched mostly in a relief role for the Astros, his first two years resulted in an ERA+ of 81 in 1990 and a 73 in 1991. Then he apparently put everything together. In 1992 he posted an ERA+ of 160 (111 innings) and then in 1993 posted an ERA+ of 148 (96.2 innings). Those two years are what likely got him traded to the New York Yankees in the 1993 offseason.
On November 27, 1993, the Astros traded Hernandez to the New York Yankess for Domingo Jean and Andy Stankiewicz.
Domingo Jean would never appear for the Astros in a Major League game. Andy Stankiewicz (fun name to spell) would play a part-time role in Houston posting a 109 OPS+ in 69 plate appearances in 1994 and a 19 OPS+ in 65 plate appearances in 1995.
The Yankees didn't do much better with Hernandez; In 1994 he posted a 79 ERA+ in 40 innings. He would return to Houston in 1996 and post a 92 ERA+ in 49.1 innings.