Twenty-year-old Rick Porcello became the fourth-youngest Detroit starter since 1954 to earn a win when yesterday he beat Seattle, 8-2. Those younger were Bob Miller, Denny McLain and Bruce Robbins. Miller ended up 6-8 in a five-year career while McLain had one great season, two very good seasons and six below average seasons (based on ERA+) before bowing out of the game prior to the age of 29. Robbins ended up 7-5 in two seasons.
That's not a great track record.
I'll find solace in Hal Newhouser, who won nine games at the age of 19 and went on to a Hall of Fame career.
Dan Petry is an in-between case. He joined the Tigers at 20 and went 93-64 with a 3.49 ERA (ERA+ 116) over his first seven seasons. He was 32-40 with a 4.85 ERA (ERA+ 84) his last six seasons. Moving away from the Tigs, how about Dwight Gooden? As a 20-year-old he put up one of the greatest seasons ever for a pitcher. For his first six seasons, he was 100-39 with a 2.64 ERA (ERA+ 132). The next 10 years, he was 94-73 with a 4.24 ERA (ERA+ 99).
C.C. Sabathia got his first win at 20 and has yet to see a dropoff. He is one of the rare players I could find to be successful, but I did a very limited search on baseball-reference.com. Pedro Martinez made his debut at 20 (only 2 games) and has survived nicely. We still have to wait and see with Felix Hernandez.
Maybe the most sustained goodness belonged to Bert Blyleven.
Oh, there's Rick Ankiel ...