I wouldn't sign him to an extension either not because I think he's bad, in fact I do believe he's been good for the Angel organization.
When his contract is up (or possibly before depending) it'll be time for a change.
And I have to agree with you about the people that think he's (Scioscia) the worst in the game! It's hard to take them seriously when their pov is distorted by a bias. When it's all said and done baseball historians will judge Scioscia's managerial career very favorably.
Oh, and btw, since when has A-Rod had any credibility?