The spring marathon season boiled up spectacularly this month with two epic races in London and Boston.
Just as the quality of Emmanuel Mutai's comprehensive victory in the London marathon was registering, in Boston on the following day two men produced times way inside Haile Gebrselassie's world record of 2:03:59.
Geoffrey Mutai's and Moses Mosop's clockings of 2:03:02 and 2:03:06 would have left 'our' Mutai (2:04:40) back in Birdcage Walk had they been achieved in London.
But you will not see them above Gebrselassie's world record on any list without an asterisk. That is because Boston is regarded as an aided course.
The direct distance between the start and finish points (the 'separation') is around 25 miles, and it features an overall elevation loss more than three metres per kilometre. Basically, the competitors ran in a straight line for most of the race, ending up at a point 136m lower than the start.
It is the separation clause which is most significant here, because in spite of the overall drop, Boston features a number of challenging hills.
IAAF Rule 260.28a states: "The start and finish points of a course, measured along a theoretical straight line between them, shall not be further apart than 50% of the race distance." In Boston the separation figure is 91%, making it an extreme example of a "point-to-point" course.
The purpose of this ruling is to eliminate courses which can benefit from wind assistance, and that is exactly what happened for Geoffrey Mutai, Mosop and the rest.
The Boston course is north-east, and on the day of the race there was a south-westerly wind measured at up to as much as 14mph. The maximum allowable assisting wind for track events is just two metres per second or around 4.5mph.
If Usain Bolt had run a 100m race on a track in the same direction and the same conditions as the 2011 Boston marathon, it would have been regarded as heavily wind-assisted. In such optimum conditions, it is not surprising that the final times were so flattering.
In London, Emmanuel Mutai had no such benefit because the London course meets the criteria for world records set out by the IAAF.
As the crow flies, the distance from start to finish was seven miles or 25.7% of the total race distance, and the overall drop was just 34m.
The approved thresholds for marathons are 21.0975km for the separation and one kilometre per metre drop (42.2m). Any wind blowing behind the London field in the first three miles would have been in their faces in the next four.
So, official world records can be set in London, as is the case with the current women's mark held by Paula Radcliffe.
Emmanuel Mutai's performance in London is intrinsically superior to that of Geoffery Mutai in Boston, because of wind assistance enjoyed by the latter and his compatriot Mosop.
Geoffery Mutai's was a freakish performance, averaging 4:42 miling for the entire distance on his marathon debut. It should also be noted that, collectively, this was the fastest-ever Boston marathon for women.
No legitimate record can be set on the current Boston course, but theirs is the world's oldest annual marathon, dating back to 1897, way before any world record rules were laid down.
It is not the only established race in which a world record cannot be run. Our own Great North Run, like Boston, is regarded as aided, being both downhill and point-to-point.
The recent New York half-marathon is another which does not meet the criteria set out in IAAF Rule 260.28, so Mohammed Farah's super 60:23 win there last month can only be regarded as a UK best, not a UK record.
A simplification of the rules would be welcome, but that would be unfair to organisers and competitors on courses like London where the advantages have been ironed out. On the other hand, it would be unthinkable to change such celebrated and historic courses as Boston or the Great North.
A formula which takes account of all the various factors and spits out a list of adjusted times which could be compared directly would be another way to proceed, but sadly it would most likely be impractical, if not impossible, to blend together all relevant parameters to compute the level of aid afforded in the different types of road races.
The IAAF have got it about right, but even their criteria are not as stiff as those of the authoritative Association of Road Running Statisticians (ARRS) whose separation threshold is 30%, not 50. Keeping on top of road records is a complicated business.
All of which makes the job of providing statistics that enhance rather than complicate the message near-on impossible.
What can be said for now is that the world marathon best is 2:03:02, the world record remains at 2:03:59 and some promoter is going to have to pay a lot of money to see the race we did not get in London or Boston: Mutai v Mutai.
Men's marathon all-time top 10
* = performance on aided course
1. 2:03:02* Geoffrey Mutai (Ken) Boston 2011
2. 2:03:06* Moses Mosop (Ken) Boston 2011
3. 2:03:59 Haile Gebrselassie (Eth) Berlin 2008
=4. 2:04:27 Duncan Kibet (Ken) Rotterdam 2009
=4. 2:04:27 James Kwambai (Ken) Rotterdam 2009
6. 2:04:40 Emmanuel Mutai (Ken) London 2011
7. 2:04:48 Patrick Makau (Ken) Rotterdam 2010
8. 2:04:53* Gebregziabher Gebremariam (Eth) Boston 2011
9. 2:04:55 Paul Tergat (Ken) Berlin 2003
10. 2:04:56 Sammy Korir (Ken) Berlin 2003