I haven't seen an announcement of this and there's nothing in the Press section of the SF Opera Web site yet, but on the cast page it now appears that Friedemann Röhlig is out, Richard Paul Fink is in, as Edward Teller.
I saw Fink first as Escamillo in Carmen some years back; the role didn't suit him at all and I dismissed him out of hand. In 1999, he was a decent Kurwenal in the Met's Tristan, and I thought, "Oh, okay, good."
I got one of the happiest surprises of my opera-going life in 2001, when he was a brilliant Alberich in the Seattle Ring. Two years later, he was excellent as Klingsor in Seattle's Parsifal. I am looking forward to his Teller; I expect he will be excellent or better.
Update: There is a discussion of the cast change in Georgia Rowe's Classical Notes column on the Contra Costa Times Web site.