When players compare themselves to other players, it's not in terms of what they expect to produce on the big league level. Rather, it's how they approach things on the field. Hill talked elsewhere about his pitches, specifically his 12-6, and compared what he did on the mound to other pitchers. I never had the pleasure of watching Koufax, but I believe he threw mostly (if not exclusively) his curveball and his fastball. And like Koufax, Hill was a strikeout pitcher. Hill obviously doesn't have his fastball, but especially in the minors, those were the two pitches he relied on. It's a fair comparisson if you're letting people know how you go about pitching. Not many people would be crazy enough to actually say that they're the next Sandy Koufax, and that includes Hill.