I like this concept. All of this is very subjective, but I definitely agree there's a difference between being one of the 32 best SPs, & that elite tier of SPs that are the real difference-makers come postseason time. For me, prime Nelson isn't close to prime Sheets. And I like Nelson. It's not close. Sheets' 2004 season is a case-in-point. He was an ace that season. It may be the best losing season of any pitcher in history. For me an ace K's 200, pitches 200IP, and keeps his walks down. There are exceptions to this but I differentiate and ace from a #1. There are five or six "aces" in baseball in my opinion.