I think he has shown much better than Estrella, this year, so far...albeit a very limited sample size. JP coming off of injury hasn't helped and opened up more minutes for Cade. For a guy who barely touched the floor as a freshman, he's averaging 6 pts/4 rebs while shooting 73%. He's also not turned the ball over even once in 53 minutes.
I do understand your concerns about his role and how he fits, but right now, he is pulling up the slack for JP, who I agree has a higher ceiling. Will he ever get fully healthy and stay there is the question. Feels like he is always dealing with some ailment.
Phillips reminds me a lot of John Fulkerson. Fulky took a little while to get going, himself, and was a bit of a role player his first few years, partly because of injury.