The new facts:
2:08:36 PR, Boston 2014
WEATHER
Very close to perfect:
http://www.bostonmagazine.com/news/blog/2014/04/22/perfect-marathon-mondays-weather/
(Some may argue it was a bit warm, but most of those complaining were mid-/late-packers. Average temperature during the elite run was apparently 51F and wind was negligible.)
COURSE
This has of course been debated ad nauseum here. I will open this thread with my own estimate of a 1:30 differential compared with Berlin or a similar course (pancake, minimal/gradual turns). ie I am saying Kipsang could roll around 2:05 flat on the Boston course.
(Since the 2010 legit-weather course record of 2:05:52 was set by a guy clearly without WR potential (the solid-but-not-world-beating Robert Cheruiyot), it is very dubious to argue a differential of more than 2:30.)
If we give Meb 0-15 seconds for weather, 1:30 for the course and 15-30 seconds for perfect team of pacers towing him to 30km, that totals 1:45-2:15.
Perfect-everything marathon ability for Meb = 2:06:20-2:06:50?
GO, MEB!