Naturally a Democratic strategist is not going to call attention to vulnerable Democrats...I'm surprised he included even one, but maybe felt he had to or else it would be captioned "the ten most vulnerable Republican incumbents."
Stuart Rothenburg is not a Democratic strategist, nor does he have any affiliation with the Democrats. He's one of the most honest forecasters out there, and in the past two election seasons he's been out front in spring saying "sorry Democrats, the wave you're hyping isn't happening this year."