Having the "stuff" to be a top-5 pitcher means more than having just 2 electric pitchers. You said that he had the stuff to be a top-5 pitcher, I doubt that he has the right pitches to do it. If you're a starting pitcher, you won't succeed based on a fastball and curveball alone.
Furthermore, can he sustain 100 MPH of velocity and still remain healthy? There are a lot of pitchers that cannot. There are a few that can (Verlander, Josh Johnson, and Ubaldo Jimenez, off the top of my head), but of the three that are list, all of them throw their secondary pitches about 40% of the time, all three of them throw at least an average changeup (in fact, Verlander and Jimenez's changeups have very strong run values). Feliz has not shown the ability to throw an average changeup, and until he does left-handed hitters will destroy him.
Having two very good, electric pitches does not automatically make you a top-5 pitcher. He has two pitches that could very well exist in the arsenal of a top-5 pitcher, but he doesn't come close to having the stuff that a top-5 pitcher would.