According to BRef's player index, there have been 11 pitchers since 1997 to start at least 10 games in their first MLB season and walk more than 5 per 9 at the age of 24 or older. Here they are in alphabetical order alongside their career and peak season bWAR:
Micah Bowie (negative)
Octavio Dotel (15.7, 4.2)
Ryan Glynn (negative)
Angel Guzman (1.4, 1,7)
Joel Hanrahan (4.3, 2.5)
Aaron Harang (23.5, 6.0)
Aaron Heilman (2.1, 2.2)
Kazuhisa Ishii (0.2, 0.7)
Justin Miller (1.4, 1.1)
Sean Newcomb (NA)
Blake Stein (2.8, 1.6)
So if the past is any indication, Newk has a...
10% chance of being Harang (a pretty damn good starter for a 3 year stretch in his age 27-29 seasons)
10% chance of being Dotel (a legit high leverage BP arm)
80% chance of being Justin Miller (basically a bust)
I think Newk probably has a better than 20% chance of a solid MLB career, but I also think it's instructive to take a look at exactly how poorly pitchers this old with this bad of control actually fair. It's also interesting to see just how few guys are allowed to start 10+ games with such poor command.
Micah Bowie (negative)
Octavio Dotel (15.7, 4.2)
Ryan Glynn (negative)
Angel Guzman (1.4, 1,7)
Joel Hanrahan (4.3, 2.5)
Aaron Harang (23.5, 6.0)
Aaron Heilman (2.1, 2.2)
Kazuhisa Ishii (0.2, 0.7)
Justin Miller (1.4, 1.1)
Sean Newcomb (NA)
Blake Stein (2.8, 1.6)
So if the past is any indication, Newk has a...
10% chance of being Harang (a pretty damn good starter for a 3 year stretch in his age 27-29 seasons)
10% chance of being Dotel (a legit high leverage BP arm)
80% chance of being Justin Miller (basically a bust)
I think Newk probably has a better than 20% chance of a solid MLB career, but I also think it's instructive to take a look at exactly how poorly pitchers this old with this bad of control actually fair. It's also interesting to see just how few guys are allowed to start 10+ games with such poor command.