Could a surface officer in the German Navy of WW2 be given command of a submarine?

In CS Forester's The Good Shepherd, destroyer Keeling and corvette Dodge engage and destroy a German submarine who, on reflection, 'handled superbly, far better than she had been handled under water'. This leads Commander Krause to wonder if the sub captain might have been 'a surface ship officer given command of a submarine after insufficient underwater training and experience'. (For those who've seen Greyhound but not read the book, this is indeed adapted - sans the view into Krause's thoughts.)

How likely would it have been that a surface captain could have got a sub command? Especially someone who seems to have been an experienced surface officer, based on how Krause rates his handling of his boat.