In a nutshell you got it. Of course I’m not speaking for every d-1 college here, or any one in particular.
But you have athletes even good ones who are not polished, getting more reps under there belt. And are consuming more then they burn.
Are the people at t-nation not gaining muscle or not gaining any weight? If there not gaining weight its because they aren’t consuming enough calories. You cant gain anything if your not taking enough in.