I think a lot of our disagreement stems from our expectations for an Ace as you implied. When drafting in the top 5, let alone the number 2 overall pick, I want to go get that elite Ace. I'm not looking for James Shields, who is a very nice pitcher, but instead I want that guy who is going to go out and dominate on the mound year in and year out. Not have 1 or 2 dominant seasons mixed with a bunch of mediocrity. There is a difference between an elite Ace and a fringe Ace, for lack of better terms, and the 8 pitchers I listed seem to fit that elite ace description. That is why I have them listed. That said, if you want to expand to just a more general term "ace" you still have the pre2001/post2001 issue to deal with because it is evident in your data too. Seven out of eleven of your aces acquired since 2001 came in the first round. To me that says you need to draft a pitcher in the first round if you want an ace. Of your 4 who weren't drafted in the first round one is an international (Felix Hernandez), Josh Johnson has had 1 great season and then a bunch of nice but not great years, Dan Haren has had a few real nice years but also some pretty mediocre years, and Gio Gonzalez has only pitched 3 full seasons in the majors. Just for comparison's sake: Pre-2001: 25% were 1st round picks (this is using my stricter elite ace standards too. If I added in the more fringy aces this would drop to below 20%) Post-2001: 64% were 1st round picks (using my data it's 88%) I have yet to see that explained. Until then I contend any pre-2001 data is irrelevant.