It's hard to construct an accurate system to divide all of the top MLB SP'ers into 5 categories of 30 each.
To get a sample size of 150 pitchers (30 teams x 5 SP'ers) the sample size needs to be around 75 IP. If you use that, then you have some smaller sample pitchers that show up on the ERA, ERA+, ERA-, FIP and other non cumulative value stats leader boards, most likely undeservedly.
Since most #5 starters are interchangeable, maybe getting the sample size to 120 is best, and all the rest are #5's or better. This is flawed, too, for many of the same reasons. The sample size is 100 to get 120 pitchers, and someone going 100 IP vs someone else going 180-200+ IP is apples to oranges in many ways (unless you use something like fWAR, which accounts for longevity.)
Here is a look at the top 120 rankings:
fWAR: #1 Crochet (4) & Gray (20), #2 Bello (59) Gio was a #3 at 64 and nobody else had 120 IP.
ERA-: #1 Crochet (9) #2 Bello (31 is almost a #1) Gio was a high #2 (33) and Gray is a #3 at 77.
FIP: #1 Crochet (8) #1 Gray (21) High #3 Bello (62) & Gio (64)
Does this get us any closer to knowing if Gray or Bello should be called a #2, a #3 or something else?
Then, we have to try and project 2026 from past numbers: 1 year, 2 years, 3 years???
Geeeessh!