will it be easy to make mods for this game? I am thinking with the inclusion of teams from the 1960's and 70's, will it be possible to a historical mod and create other courts/teams from the historical teams.
It's difficult to say before the game comes out and we're able to take a look at the files. Assuming the file formats don't change too much, it shouldn't be too long before the community has everything worked out. The inclusion of so many historical players right off the bat certainly facilitates historical mods, no question.