Here's the crucial thing about the TTU program - they just went to the National Championship game with mostly 2* and 3* high school recruits leading their team. Their players out-played and over achieved their high school ranking, likely based on lots of variables - one of which would be really good coaching.
Winning & good recruiting are usually chicken and egg - you usually can't win without good recruits, but you can't get good recruits if you're not a winning team. This is where Illinois is stuck right now, and you either have to start winning with what you have so that good recruits are interested based on your success (like TJH, for example), or you have to start landing surprise recruits who are willing to buy into a losing program.
So far, with Ayo, Kofi, Tevian, and Trent all being at-or-near Top 100 recruits, they've bought into the idea of turning around a losing program. Now you need to win to get the recruits that want to be part of a winning team. That's why this year is crucial. Illinois needs to perform/over-perform with the guys they currently have. Some of that is on the players and some of that is on the coaches.