With the economy being such a major issue, Warner's record of managing Virginia, and his business experience, leads him to an even bigger landslide than Obama's.
You have to understand someone's campaign ability versus someone's record. McCain had a long list of accomplishments in the US senate, but did not project them well to the public. On the other hand, Obama has campaigned absolutely flawlessly, but has accomplished near to nothing.
You have to understand that Mark Warner would not have had nearly as many grassroots efforts, nor as much charisma as Obama. He may have a decent record, but if you actually think he would have done as well (or better, as you seem to believe), you are living in a pipe dream.