Whether Underwood and Antigua had anything to do with Black's development or not, it will be a huge selling point to recruits.
Leron has gone from frustrating because you could see his potential but he wasn't making the most of it to a stud. I'm selling the heck out of that you both Liddell and Okoro, Whitney too.
Same thing goes for Aaron Jordan. He went from can we politely ask this kid to transfer to a legit player. Underwood needs to sell it.
Unless some recruits are diehard Illini fans, a lot of these Illini "success stories" do not really register on the national level recruiting. National recruits want to see a prominent team, a contender, or players making it into the NBA, etc. Improvement of some players who are not big names on the national scene or do not make it to the NBA become less visible/important to them, especially when the team itself is not making some noise.
That is why Illini coaches need to be strong recruiters, because we simply do not have many selling points, so much of what we are selling is "promise" of success. Playing time and Ayo are probably the two biggest selling points right now. JMO.