Mike has made 5 starts in the majors...two great starts against arguably the worst offense in baseball, and 3 bad starts against SF, Miami, and Toronto. Now this is a small sample, but I've seen each of this starts except the Jays one and he's never looked like he's going to be anything more than a number 3 guy. Most reports on him were that he already had a good feel for pitching (which doesn't appear to be the case) and that he has good control (which hasn't been the case). His slider has mostly looked average to below average as has his change up. His sinker has shown signs of being a plus pitch but for the most part has not been. He seems to work up in the zone a lot which is never good for a sinker ball pitcher. His velocity has been all over the place (dude was below 90 mph on his fastball multiple times against Toronto which I saw the condensed game on mlb.com). I know he's young, but from looking at him it doesn't look like he's has more "growing into his body" so I don't see him adding velocity.
It's possible we haven't seen typical Soroka yet, but you would think we would see signs of this young guy who already has a feel for pitching with good control and this has only been the case against arguably the worst offense in baseball.