Doing a little sim league research, I made a spreadsheet with all of the starting pitchers from this season in MLB. I included everyone who had been primarily a starting pitcher this season and who had made more than a few starts.
I hadn't looked lately at where Kenny Rogers, Chris Young and Ricardo Rodriguez would fall against other SP's (including non-qualifiers) in things like ERA, etc. RicRod has only made five starts, so he's boarderline for this. But anyway, very crude setup (no park adjustments or anything, but I'm not really trying to truly assess anyone, just where guys rank against everyone else in raw performance), and pretty premature, but for this non-steroid season, I noticed:
Going by WHIP and ERA, it's pretty easy to identify who has been a #1, #2, etc. so far this season.
28 SP's have a 1.2 WHIP or better
58 have a 1.3 or better
94 have a 1.4 or better
119 have a 1.5 or better
So, for instance, if you have a 1.24 WHIP, you're a solid #2 in terms of WHIP.
33 SP's have an ERA below 3.50
64 have an ERA below 4.00
91 have an ERA below 4.50
118 have an ERA below 5.00
So both of those sets are pretty close to 30-60-90-120 intervals. Also, if you put ERA and WHIP together, the following 28 pitchers rank in the top 45 of each:
Johan Santana has an abberational ERA, but is 8th in WHIP. So if you count him, you're pretty close to the 30 best pitchers so far this season.
Rogers falls in this group of #1's. Chris Young would be a low #1 in terms of WHIP, and a #2 in ERA. Rodriguez would be a #2 in WHIP and a low #2 in ERA (again, he doesn't really count since he's made so few starts).
So I guess you could say all of this is (unneeded) confirmation that the Rangers have had three really solid starters to go along with a few #5's or worse, in Drese, Park, Astacio, & co.