It's true the Pirates haven't had any all-time great pitchers. When they were often in contention and winning the occasional World Series along with many division titles in the 1960s, '70s and early '90s, they were known for their hitting more than having great pitchers.
But there were some other notable pitchers during that time frame besides Drabek, Candelaria and Tekulve. Vernon Law won the Cy Young Award in 1960 and finished with 162 career victories. Bob Friend won 197 games (and later became an Allegheny County (Pittsburgh) county commissioner as a Republican).
Elroy Face was one of the first prominent closers. He pitched in 848 games and is best known for his 18-1 record in 1959. Steve Blass was one of the top pitchers in the NL from the mid-60s to the early '70s until reporting to spring training in 1973 unable to throw the ball over the plate. It remains the most mystifying example of a pitcher suddenly and completely losing his stuff. 6'6" Bob Veale was one of the league's premier strikeout pitchers in the '60s.
Rick Rhoden had some solid seasons in the '80s and finished his career with 151 wins. Of recent vintage, Gerritt Cole was a top pitcher before owner Bob Nutting, per his m.o., let him go elsewhere rather than ink him to a market value deal. Maybe it'll be different when Skenes is eligible to become a free agent but I highly doubt it. By that time top pitchers will likely be making $100 million or more a year or close to it and Nutting will never shell out that kind of dough.
Honorable mention goes to Dock Ellis, who had some good seasons in the '70s and allegedly threw a no-hitter while tripping on LSD.
