Zero year old players after erasing league history
 

I run a fictional simulation for 15 years, erase all league history and then find hundreds of players age 0, with a few up to age 6. Not sure how to edit them all either as some are in MLB too and all throughout minors.

I had that problem in OOTP18. It happened when I copied a league template, erased the players but started the league in an earlier year. I gave up trying to fix it and just started my league from scratch.