First off.
Dempster wasn't that bad vs the Yankees. I think your jumping the gun to suggest he's gonna pitch to a 5.40 ERA all year. I doubt we'll see him in the 3's but a low 4 is both possible and passable in my opinion.
Doubront is a young hard throwing lefty who struck out more than a guy per inning last year. He only lasted 5 in his first start but he didn't walk a batter which is a solid sign considering that that was his big issue last year.
Lackey had an arm strain and tests show no structural damage to his arm, to say he will be shuttling in between the mound and DL all season is just unjustified pessimism. He had a scare but we later found out that he's fine. He very well may have injury problems this year but so might the rest of the rotation. Not to mention that he's in the best shape he's ever been in with the Red Sox and looked the best he ever has with us on Saturday before leaving with his injury, getting good velocity on his pitches and striking out 8 over 4 1/3.
Lester and Buch have indeed been awesome to start the year, that much I agree with, but saying that the back half of our rotation is "bad, really bad" is unbased hyperbole on your part.