I'm not advocating dumping Garrett for Lovie, but Smith is hardly a joke. He appears to inspire intense loyalty in others -- Marinelli, for example -- and has taken two teams with obvious questions at QB on deep playoff runs (once to the NFC Championship game and once all the way to the Super Bowl), largely on the strength of a defensive scheme for which he deserves much if the credit.
From the perspective of their credentials, one could easily see suggesting that he might be a better man for the job than Garrett. I'd still take the guy we have for now, but my choice would not be based upon a straight forward comparison of their credentials.