I kept the faith and keep playing him as my first choice AMC in my midfield two, has started putting in MON performances and my coaches are claiming he could potentially become world class. He is on a sharp upward trajectory with his stats, and the first team exposure has definitly helped.
I'd probably recommend gently easing him into your first team against weak sides, and he should hopefully gain in stats enough to become first choice.
I've been having him work on his stamina, which is working wonders. Kinda delighted as I was toying with buying Gotze for 50m and using Tielmanns as a replacement for Herrera, but instead Tielmanns has started becoming an outragous AMC, and I've ended up getting Matovic(spellcheck) from Inter as a possible Herrera replacement