I am in a 100+ year fictional save 1981-2097 (current year) game started in OOTP11 & OOTP12 and on my 3rd different MLB team inside the save, used real teams because like you I do not like fake MLB teams.
Now for me I have spent 5 years coaching HS team, 11 years with Pittsburgh, 55 years in Chicago and currently 20 years with Fremont 1 year over lap with Chicago cause it was so hard to let go.
To keep involved I follow players, record drafts, I have league evolution on so things change, I also have running a league a Japan league and Canadian baseball league in the same universe along with INDY and WBC, but 50 in game years ago I had a different version of WBC, I tried to create my own manually bringing players over oh boy was it a mess. I also have a Championship between all my main leagues.
I have so much history, I have college and High school; feeders so I can get lost some times in how players know each other or that dream hs team with like 3 MLB stars on it or find a guy with
one Game like this
Have I ever got bored hell ya and I tried to add something new like WBC or World Baseball Championship, I tried not playing, I even bought & played Basketball sims for a few weeks to clear my self of OOTP.
Each version of the game provides its own challenges and you have to try and adjust but also play with in your self and not take to many advantages because you are smarter then AI, the few versions of AI have been better able to get to my teams and its been fun not winning Series every year but that's always the goal.