MadduxFanII
Swallowed by Mark Bowman
That list of guys over the last 20 years, while interesting, had too many conditions. Limiting it to guys who made their MLB debuts at age 24 or older eliminates a ton of very relevant pitchers. I don't think it's fair at all to eliminate guys who made their debuts at 22 or 23 from consideration as comps. Different players mature at different rates or start from different places in development.
Lets go back to Gio Gonzalez. He debuted in his age 23 year but didn't pitch a full season in the majors until age 25. In the year Gonzalez turned 24, he pitched 98 innings for the A's with a 5.11 BB/9 to go along with a 9.94 K/9 and a 1.28 HR/9. Newk's numbers are slightly better at this point.
But, because Gonzalez pitched 34 innings the year before he doesn't appear on that list. BTW, Gonzalez hasn't had a BB/9 higher than 3.54 since 2011.
I'll confess, Gonzalez is a slightly better statistical comp for Newcomb than I originally thought. Better minor league walk rate than Newcomb (4.1/9 as opposed to 4.8/9), slightly worse strikeout rate, slightly worse homer rate. Gonzalez was always younger at his minor league stops than Newcomb, and spent at least a few of those years pitching in the notoriously hitter-friendly PCL, but there are definitely similarities there, so it's not an awful comparison.
Still, it's worth remembering that Gonzalez has put up about 25 WAR in his career. He's been a multiple All Star and he could have won (an undeserved) Cy Young in 2012. Pitchers with his minor league profile don't usually become 1/4 as productive as he has been. If Newcomb puts up Gio Gonzalez's career we should all pop champagne and do The Carlton.