Quick Rant on Assessing Pitchers

I like the website MLB Trade Rumors. However, I have been annoyed lately by every post on MLB Trade Rumors that has anything to do with a pitcher immediately breaking down to ridiculous arguments over whether said pitcher is "a #2" or a "an ace" or a "#4" etc. These arguments are worthless. No one has a real good idea what a "#2 starter" is. Is it the 31th-60th best starters in all of baseball? Is it what the 2nd best starter would look like on a good team? How about the second best on the Phillies? That one seems like it might be a pretty high standard. Can't the commentators just talk about how good he is relative to some fixed point like average or replacement level?