Not only was Boston deeper than London this year, so was Rotterdam. For that matter, Paris - where 11 people broke 2:10 - was as well. Neither Rotterdam or Paris are part of the World Marathon Majors series, but they have very competitive fields.
Although it's not fair to compare times at Boston with the other three courses, due to Boston's hills, here are the top 10 times at the big marathons for this month:
Paris Rotterdam Boston London
2:06:40 2:04:48 2:05:52 2:05:19
2:07:10 2:04:55 2:07:23 2:06:23
2:07:10 2:05:13 2:08:39 2:06:55
2:07:59 2:05:23 2:08:41 2:07:33
2:08:28 2:07:01 2:09:26 2:08:04
2:08:31 2:08:53 2:10:53 2:08:46
2:08:47 2:09:49 2:11:48 2:12:03
2:08:59 2:10:29 2:12:04 2:13:40
2:09:25 2:11:09 2:12:24 2:14:39
2:09:36 2:11:28 2:12:33 2:16:38
Didn't Boston pay out more prize money? I remember in 2008 they upped the purse at Boston and, at the time, had the highest purse of any of the marathon majors. Did London up theirs yet again?
It was weird seeing the pacers putting their hands down telling everyone to slow down. They were pointing at people, looking as if to tell them to slow down aslo. One of the pacers seemed to get upset and dropped back a bit at one point, very odd. It also looked as if some of the runners were telling the pacers to get their bottles.
Obviously, "deeper" is a highly imprecise term (do you look at the quality of the top five, ten, twenty, fifty, or one hundred?), and looking at finishing times rather than the quality of the field to determine the depth of the field (as one or two posters seem to have done) is not entirely sound. But I agree with your observations about London. Its reliance on pacemakers has made most of that race unwatchable. (Ever try to explain to someone unfamiliar with roadracing that none of the leaders in the race are actually competing in the race?) And since other cities have apparently devised courses that are even faster than London's, the pacemakers at London don't even serve the silly goal of creating world-record times anymore.
The Eschende marathon was almost as "deep" as London by some of these measures... 2:16:30 would be 9th in this small Dutch race of about 500, and would've been 10th at London.
This years results do show this but there were quite a few athletes affected by travel. The majority of Boston's elites were already in when this occured. This was not the case with London and only got the main guys in. Would be interesting if you looked at this over say the last 5 years excluding this year.
That would probably give a fairer account...