YOUR definition of #1, etc., you mean.
I define a #1 as top 15 in the majors, #2 at 16-45, #3 as 46-75 (i.e in the top half of each tranche).
A #4 is a pitcher who can start 30 games above replacement level and give you close to 6 IP per start (saving your bullpen) [even using 100 IP, 91st pitcher is about 1.5 WAR/4.4 FIP]
A #5 can start 25-30 games at replacement level, so you don't have to use a negative WAR pitcher (because most teams end up with negative WAR pitchers starting 30+ games).
I don't care about stuff, I care about production. Tools matter to scouts, production matters to GMs. So my rankings are relative to what other pitchers actually do.
Now the question is what do you use, WAR, FIP, etc. to rank them, but in most cases it'll be similar, WAR takes into account quality pitchers who are injury prone (both how well and how often you pitch count - because when you don't pitch, your team has to use their 6th best SP).
2016:
Hellickson 29th WAR (FG) - 38th FIP qualifying (65th 100+ IP)
Eickhoff 45th WAR - 47th FIP qualifying (80th 100+ IP)
Nola 52nd - 9th FIP (100+ IP)
Hellickson could garner a nice haul if he continues to pitch like he has since joining the Phillies, he's better than most teams' 2nd/3rd starting pitcher and could solidfy a rotation for a stretch run. No, he's not a guy you want starting the first game of the playoffs, but first you have to get to the playoffs, and second you need someone to start the 3rd game.
Nola's velocity is up significantly this year, we'll see if he maintains it, but it's pretty usual for young pitchers to add 1-2 MPH in their early 20s. He won't turn 24 until June.
Eickhoff at 27 is maxed out.