Should be easy enough to make this work.
In the current "View Style : List" of players, there is a space above Next Game |Last Game.
Put new Tabs right there, Games | Contracts | Notes
Games : shows what we see now.
Contracts : shows contract expiry, morale bonus or whatever, if Free Agent shows number of offers for that player.
Notes : shows custom Notes.
Then add a tick box somewhere to Open All Player Builds.
Even if you just get a Grease Monkey Script to do something like that, I'm sure Bort would look at making it part of GLB?