If you think about it, it isn't all that hard to comprehend. For me, I gave the marginal wind advantage for athletes such as Geoffrey Mutai and Moses Mosop at around 75-90 seconds, or 2:04:17-2:04:32 for Geoffrey and 2:04:22-2:04:37 for Moses(at Boston with little wind but with perfect temperatures). In comparison to last year, I would say since they did have a tailwind last year about 40-50 seconds and maybe a minute factoring better temperatures on this years race, so just over 2:04 in my opinion would be the time they would have run last year in the same conditions.
I would also like to add that if the Boston times were accepted as legitimate for record purposes, then Ryan Hall would now have a faster marathon personal best than Samuel Wanjiru and only three seconds slower than Paul Tergat...If that wouldn't make you wonder whether there are some windy facts which incontrovertibly explain this, then what would?
For Ryan, however, it is a different story. He is a much larger surface area in total so it's probably about 1-1.5 seconds a mile more assistance for him counting he was in front catching the tail wind the best of all athletes and of course he is bigger than the other athletes. That's about 25-40 seconds over the marathon better than the other Kenyan and Ethopian athletes. So for Ryan I would say about 100-115 second wind assistance.
Which in turn equates to about a 2:06:45-2:07:00. Nothing extradoinary for him. He was bound to have a breakthrough performance and he's run Boston so many times and really ran for time in this race especially, and it's not exactly surprising he got that considering he looked very mentally fit before this race. He also looked like he managed to get his training together over the last few weeks before the marathon, and said he felt better than last year. All the top three have definately shown they have the speed and the stamina and the training to mantain that pace and Ryan was destined to have a breakthrough run.
Plus, I have a feeling that Boston is highly overrated as a slow course, and if run correctly is probably as fast(even without wind aid) as any of the other majors or maybe slightly slower.
Considering the ability to run hills well of the top 4 athletes(Mutai running Cross so he was very hill ready, Mosop of course was said my Renato to have been doing hill training and doing very well, Gebremariam of course former WXC Champ and NYC marathon winner so of course a natural hill runner, Hall having run 2 previous Bostons before this race and a New York so very fit and ready with the hills)we can actually predict that if not a tactical race and run for time and with a rabbit(Hall) setting the pace and keeping it strong the first half but not too brutal and with the second half being fast and tactical(not in a slow, but fast, way) we can say it is just as fast as the Europe marathon. The reason for this is you can really attack the Newton hills if prepared and not loose a lot of time if you run smart and after that you can use the downhills toward the latter miles to relax and gain time. So I'd even go as far to say it is faster.
Either way, I'd say that Geoffrey Mutai and Moses Mosop are high ~low 2:04 runners on a course like Berlin, and athletes like Gebremariam and Hall in the 2:06 range. If really broken down and considered the variable factors in this race, you really come to see that the wind was only one of many variable facters(Perfect Temps, Basically a rabbit setting the pace in the first half, Uphills used as quick, tactical miles and downhills still used to relax and gain more time still, the wind of course, Some of the current best marathoners in the world running who have high strength and can handle courses like these, Perfect competition for both spots 1-2 and 3-4 and basically set up to run fast times, and other many smaller, but helpful, variables that helped the times).
All in all, I don't know if we will see any low-2:03:00 or even sub-2:03:00 times on the European circuit yet, but you can bet that this Fall fast times will definately occur and these athletes will surely be mixing it up in the big races. I predict the world record will fall and Mutai and Mosop will possibly be sub-2:04:00 runners by the time the year is over. Hall will probably continue to prepare for the marathon trials, but if he really focuses on a Fall race and gets mentally pumped and physically ready I can see a sub-2:06:00 in his future. It's certainly possible. I think what we saw in Boston was truly amazing and an indicitative of just many more future races to come and many more amazing times to be run. Don't be surprised if this fall the world record falls and several athletes go under 2:04:00, because it is certainly a possiblility.