I've never managed to have a decent knuckleballer... Although I can't say I've ever gone out of my way to draft / develop one either. In an old league that I think I started on OOTP12... and that is either long lost or has long since been banished to a USB stick in my junk drawer... I did have a back of the rotation knuckleballer during some lean years.
About the only thing I remember about him was years after he had left my team, he was the only OOTP pitcher I can ever recall seeing retire with 300+ losses when using standard modern day settings. I think his career record was 210-305 or something like that... with an ERA well north of 4.00... When I noticed him on the "recently retired" list, I couldn't believe he had still been getting rotation gigs in to his mid 40s. Over the ~80 year history of that league, he was first in career losses by roughly 100... and first in career IP by roughly two gazillion.
Memories can get fuzzy, so if I stumble across a backup of that league, I'll see if I can resurrect it just to check if his numbers were as bad as I remember.
But now that I read about some of these success stories in this thread... I might just keep my eye open and try to find a gem. I think it would be pretty cool to ride a knuckleballer for 275 innings a year for 25 years.