If the team sucks next year, then you're not getting a 'contending team every season of his contract with him performing well every year' The fact that he can't pitch everyday is why this is a horrible contract- you're dumping massive resources into a guy who plays every fifth game- that's excusable if he's at least dominant when he does pitch, but a waste if he isn't and a horrific waste if it means that you're hampered with the rest of the roster
I hear this logic time and time again, but it simply doesn't hold water. A starting pitcher has FAR more impact on any game that he is pitching than any other player besides the OTHER starting pitcher. One only look at their salaries to see the value they have. If they weren't worth it teams would lowball pitchers and pay exhorbitant salaries to position players only.