Sorry folks, haven't the time to read the whole thread. However, I have spent a lot of time watching both (Pedro and Roger), and researching both.
Using saber metric values such as ERA+, DERA, and the like, Pedro is easily and far away the greatest pitcher of all time (through his career so far) per inning. ERA+ is probably the easiest metric to understand that sheds light. Pedro is a 166 - so you ask? Well ERA+ is all the guys in a given league in a given year, with park corrections biased to 100, IE the average guy would get a 100. Pedro is has a 166. His next closest rival w/ over 1500 innings is Grove who has a 148. Roger is about a 143 or 142 (putting him around 9th or so lifetime). Pedro's ERA+ will fall, perhaps under 160 before he is done.
Roger is about done now - just 350 to shoot for if he wants. The argument for Roger is he has many more innings then Petey. A ratio of about 1.7 to 1. So do you want many more innings at a somewhat lower value, or less innings at more? I have to take Roger's career, but for one game or one season, Petey is the guy.
If you like Koufax you like Pedro, if you like Cy, WJ, and Warren, then you lean towards Roger.
I know that nobody has or likely will touch Petey's double in '99 and '00. If you look up the ERA+ values you see a guy named Keefe from the 1880's has a better season then Petey's. But that was with contact hitters and he was 50' away, hardly the same game.
All I know is the Sox had both of them, and I saw them pitch many times, that's pretty damn good for the Sox and for me.
W