Tromala
Let's take a look at the FIVE athletes you mentioned as see what they had accomplished or signficant performance BEFORE the pb's you listed:
Benjamin Limo
-he was 4th at World Short Course the year before
-he ran 13:07.38 the year prior
Eliud Kipchoge
-ran 13:48.0 at altitude at age 16
-at age 17 placed 5th at World Jr X-Country
Moses Kiptanui
-don't know why you put his name on the list they was a world class steepler (sub 8:05) before he started dropping his 3000m time you mentioned
Kenenisa Bekele
-9th World Jr X-Country at age 16
-2nd at World Youth 3000m
-2nd at World Jr Championships
Daniel Komen
-ran 3:29.46 in 1997 before he dropped his 3000m time you mentioned
As you can see all the athletes you mentioned showed some type of REAL ELITE promise before dropping their personal best you mentioned previously. So my friend you are 0 for 5 (.000%).
Yes Sergio Sanchez could be cleaned but during his WHOLE career he never hinted at the ability or had any performances that would indicate he was capable of the year he is having SO FAR in 2010.