I know Larry Rawson said the women "unofficially" went out in 4:40 for the first mile (and it's cited in the front page analysis of the men's race) but it didn't happen, not even close. Kipyego's 2k split was 6:26 (with four other runners within a couple of seconds) and they obviously did not take 1:46 (7:05 plus pace) to run less than a quarter mile. Also, Kipyego was asked after the race if she was concerned about having company for the first mile and she said no, because she knew she was going out slower than last year.
Even allowing for the first mile being faster than the second, if the 2K is accurate (and there is no reason to believe it isn't), they didn't break five for the opener.