Yes. Tom Milone, Brade Meyers and Brad Peacock should all be able to step in the rotation, today, and provide approximate value to what Lannan brings to the table.
Minor league career:
Tom Milone - 73 GS, 3.08 ERA, 1.16 WHIP, 7.9 K/9, 1.5 BB/9, 0.5 HR/9, 5.36 K/BB
Brad Peacock - 87 GS, 4.16 ERA, 1.27 WHIP, 8.1 K/9, 3.0 BB/9, 0.8 HR/9, 2.72 K/BB
Brad Meyers - 75 GS, 2.93 ERA, 1.21 WHIP, 7.7 K/9, 2.1 BB/9, 0.5 HR/9, 3.60 K/BB
John Lannan - 62 GS, 3.95 ERA, 1.37 WHIP, 6.3 K/9, 3.4 BB/9, 0.6 HR/9, 1.88 K/BB
come on. you know all 3 of those minor leaguers can't step into a rotation and produce. if one of them pans out that would be fantastic, but Lannon has 650 of very respectable innings pitched in the majors.
you can toss Meyers out right now - the guy has an ERA of 4.95 at AAA and Peacock hasn't even reached that level yet. Milone looks very nice on paper.