Yahoo's new chief financial officer should be someone who's worked in that role at a big public company, an exec who can help with internal processes, carefully selected from a wide field. Well, that was the idea, at least, when the troubled Sunnyvale internet company started its recruitment. Funny, then, that Yahoo should end up with Blake Jorgensen, an investment banker with a San Francisco boutique, with dealmaking experience, but no background in operations. He does have one great compensating qualification: he's such a good friend of his ambitious predecessor, Yahoo's Sue Decker, that he was best man at her wedding.Kara Swisher, in an interview with Jorgensen , confirmed yesterday's Valleywag rumor to that effect . Jorgensen was always Decker's pet investment banker, winning mandates for which his firm, Thomas Weisel Partners, hardly seemed qualified. Now, as Decker maneuvers to replace Terry Semel as chief executive, Jorgensen will be a useful crony. The appointment won't help Yahoo reorganize itself; but it proves that a female executive can play corporate politics with the best of them.