From Politico's article How Burris blew it:
Indeed, Burris and his staff were not too concerned about a Chicago Sun Times report Feb. 14 that Blagojevich’s brother had asked the senator to raise money for the governor. Burris also told the paper he had submitted a Feb. 5 affidavit laying out all his contacts with Blagojevich associates, admitting much more extensive contacts with the ousted governor than he had laid out in his sworn testimony during the governor’s impeachment proceedings on Jan. 8 and the first affidavit he submitted on Jan. 5.
Burris didn’t believe these revelations to be a bombshell, and he mentioned the situation only in passing to both Senate Majority Leader Harry Reid, and the state’s senior senator, Richard J. Durbin, on the Senate floor Feb. 13. Burris didn’t even give Durbin the affidavit before the senior senator left on a weeklong Senate trip abroad.
But the Feb. 14 report suddenly dominated the news, and Burris’ team hastily arranged a Feb. 15 press conference to argue he had been consistent in all his statements and drafted the affidavit after reviewing his previous statements. But that turned into a combative appearance, with Burris struggling to explain the distinction he was trying to make between expressing passing interest in the Senate seat and lobbying to get the appointment.
You have to think Burris might not have made these elementary mistakes if he'd actually had to run for his seat. Same goes for David Paterson. Getting appointed--rather than getting elected--to a top job is definitely nice from a time-management perspective, but you miss learning some important lessons--and getting some important seasoning--in the process.