It's really about spreading your risk and drafting guys that are undervalued. Let me ask you a question. If you don't think Santana is a good value with the top 5 picks then what makes him a good value 5 picks later?
i don't think he is a good pick in the 1st round, I just think it is terrible in the first 5 picks. If you take Santana say #3 who are you getting back on the wrap around? The 20th best hitter or so is your #1 hitter or in my 14 team league it is the #24 hitter or so. The dropoff is just so huge that you are in a big hole in hitting.
I think Santana is a relatively safe pick compared to most pitchers, he hasn't had huge pitch counts and he obviously has a very stable skillset. However I still think he is as risky as say Ryan Braun or Albert Pujols because he is a pitcher. The chances of a season ending/disrupting injury are just so high with a pitcher, even one with no visible reason to be concerned. The fact that he is so absurdly good is the only reason I don't cringe at him going early 2nd round even though I agree he 'could' easily be a top 2 or 3 player value.
I hope that you will agree that we can pretty go back and forth forever.
Let's just use Mock Draft Central for instance. Instead of taking Hanley with your #2 overall, you take Santana. In a standard league your next picks would be: Santana, Upton, Berkman, Putz, Atkins. Now let's just say that you took Hanley #2 overall and then instead of Atkins, you took the next best pitcher available: Hanley, Upton, Berkman, Putz, Hamels. Honestly, I don't see a huge difference between them in terms of risk/reward.
"Think of how stupid the average person is, and realize half of them are stupider than that." ~George Carlin