Is there any way to mod the game/change source code?
 

Title is basically self-explanatory. I've been playing the game for a couple of months now, have a good amount of time on it, and I really do like the game. There are just a few nitpicky things I'd like to change about it (preseason roster limit, injury frequency, etc.). Does anyone know if there is any way to do this, or if it is just not possible?

I don't know about preseason roster limit, but you can change the injury frequency in Controls -> Options -> Edit Single Player Options.

no there isn't any easy way. It's very restrictive in terms of editing and modding.