You can't just take every player's fault, then find a similar comp and project them to have the same success.
Maddux, Johnson, whoever else
Nobody here is denying the upside Sanchez has. It's just the odds of him reaching it are much, much slimmer than others (see walk rate, ability to throw strikes, short stride length leading to future injuries).
Prospects can be looked at as currency. Right now, Mr. Sanchez's value is probably pretty high.