Have you ever heard of Chris creamers website?... Not sure how popular that is amongst OOTP users. But on their forums section under sub category concepts they have some really good graphics designers who post MLB/NHL/NFL/NBA team rebrands, concepts and fictional teams. I'm sure since it's for personal use and not claiming anything to be your own you could use some for your OOTP game. There are for sure some cool ones!
For example here is a well known user on that site who's done boatloads of concepts! This link is a complete 30 team update/rebrand. Poke around and check it out!!!
Bohob's MLB Redesign Project - Concepts - Chris Creamer's Sports Logos Community - SportsLogos.Net Forums
I have adobe illustrator and do a bunch of logo work for my fantasy hockey leagues including jerseys and such so I'll be doing logo updates and rebrands over the "years" of my MLB universe!
