Siebert only appeared in seven games for Houston during the 1975 season, performing very well though, going 0-2 but with an earned run average of 2.95 over 18.1 innings of work, even picking up a couple of saves.
He would go on to play another three years in the Major Leagues, with Houston, the San Diego Padres and finally with the New York Mets, never really more than an arm out of the bullpen, ending up with a Big League record of 3-8 and an ERA of 3.77 over 87 appearances and 129 innings pitched, along with three saves and a complete game.