In 421 games Ken Forsch posted a 3.18 ERA and a ERA+ of 108. Out of those 421 games Forsch pitched 153 games which is why we'll be covering him today in advance of game 153.
Forsch is an interesting study. As you've probably guessed Forsch pitched more out of the bullpen than he did in the rotation. There's a reason for that, he was slightly below average as a pitcher for his first four years in the big leagues.
He made his debut September 7, 1970, and finished the year with a 71 ERA+ in four starts. He would flash some potential the next year, posting a 133 ERA+ in 23 starts, and 33 games overall. The two following years he posted below average numbers, 86 ERA+ both years. From there it appears he was switched to the bullpen.
In 1974 he appeared in 70 games, entirely out of the bullpen. He posted an ERA+ of 124 in 103.1 innings. From there he would pitch almost exclusively out of the bullpen, with the occasional spot start here and there. During his time in the bullpen he posted an ERA+ of 124.
In 1979, he was give a shot to pitch in the rotation again and took advantage of it, posting a 113 ERA+, while also leading the league in WHIP, 1.069, and walks per nine, 1.8. He also pitched a no-hitter against the Atlanta Braves on April 7, 1979, only one of ten no hitters in Astros' history. The next year he was only about average, posting an ERA+ of 103, but still productive.
On April 1, 1981, he was traded to the California Angels for, Astros County favorite, Dickie Thon. Forsch would go onto to be average to above average for the Angels, while Thon would go on to capture the hearts and minds of those in Astros County.