I don't know about redshirting, but it's not just about D1 or the draft. LOTS of California D2's are chock full of JC transfers. Indeed, when we were looking into this in California at least the JC route seemed like the single most travelled route to a roster spot at a D2. One school basically told the kid that although the he would love to have him come to the school but that he rostered almost no frosh but instead asked the one's he thought might eventually earn a roster spot to co-enroll at a local JC and to play with them for the first two years at the 4 year school.