The point is that it's hard to trade Santana for pitching that will help within the next 36 months (or 24 months moving the timeline back a year). It's a great idea in theory but in practice, it would be incredibly difficult to pull off, if not impossible. If a team has young pitching close to the majors, they're not going to trade those pieces for a veteran pitcher. They'll just lean on the good, young arm that they control for the next seven seasons. So you're trading a 3-ish WAR pitcher for a few prospects that are a few years away. What do you do in the meantime as Sano, Buxton, Rosario, Berrios, et al are accruing service time? By the time this hypothetical pitcher is ready, all those guys would be at 4+ years of service time, at the minimum. If you want good pitching, you're going to have to either give up prospects or open the wallet. Trading pitching for pitching between contenders isn't really an option.