Aside from all the "whys" if a kid realizes he's not getting on the field he might as well make that spring his transfer semester (if he's going D1 to D1). He transfers and the spring and fall become his sitting out year. If he waits until the end of freshman year and rots on the bench, then sits out the following spring when he transfers he's sat out two years of college ball. And he'll only have three years of eligibility left.