But guaranteeing or even suggesting that someone will be playing when they are a junior is crazy. There will be all the seniors and juniors that were ahead of him as freshman and sophomores. More importantly there will be two more full recruiting classes. And how much can you improve while sitting on the bench for two years? Not many coaches looking for full recruiting classes of kids that won't contribute until their junior year. Sure, it happens but most juniors didn't sit on the bench their first two years. There is a better chance that the junior that doesn't play his first two years will not be a big contributor ever.
Agreed - a lot changes from year to year. Especially at the higher-tier schools that bring in large classes of JC transfers. You may have "put in your time" for 2 years on the bench, but there is still the chance that your coach brings in a JC transfer to start over you.