He's a back of the rotation pitcher (probably a number 4). I'd have no issue with him being the 4th man out to the mound but to suggest he is any better than that is ridiculous blind fan boy infatuation.
Pretty dead-on here. Lannan had a FIP over 4.5 last year, which suggested that he'd regress this year. He'll most likely sit in the 4.5-5 range for ERA through most of his career, which is good, but as you said, not something you'd want for a guy who's anything more than a 4 starter.
Hopefully, Strasburg/ZNN/Martis end up being a good 1-3 so that he can sit there.