You make a lot of assumptions that help make YOUR case, but I don't know that most people would agree with taking these assumptions for granted.
1) Clarke ran 27:39 on dirt no rabbits. FINE. He also ran 13:16. He set 18 WR's, six of them at 5k/10k. So it is established that he was the greatest against the clock of his time. FINE.
You make the case that an all-weather track is worth 2 seconds per lap? I don't accept that, as many great runners over the next ten years ran on better tracks (Lopes, Foster, Viren, Puttemans, Gamoudi, Norpoth, Bedford, Shorter) and the best they could reach was 13:13/27:30 on these tracks. I believe that every one of these runners won an Olympic medal or set a WR except Norpoth.
So unless you consider Clarke to be a 26:50 guy on all-weather tracks and these other guys to be 40 seconds back under the same conditions, you can't make a case for modern tracks to be 2 secs per lap faster.
A rabbit isn't worth that much either. Given how many 3:51-3:55 miles were run solo on dirt tracks and grass tracks in the 60's, and then rabbited attempts on modern tracks yielded only three performances under 3:50 (1975, 1979, 1979) I don't see how you can conclude that a modern track is worth even 1 second per lap, and that rabbits pile the advantage on top of that?
I would say that rabbits are worth a significant amount when they do their job right and everyone plays along. that is why today's 1500m races are SOOOO fast. They have two rabbits (everyone knows who they will be), El G files in behind them and all others file in behind him. The first on drops at 800m then the the second goes as far as he can.
I could go on and on but it is boring so I would accept that a good rabbit is worth .4 a lap compared to a fast race with some leaders in front of you. ~.6 a lap if you run solo.
I would also accept that a dirt track is slower by about .4 a lap. These things added together make for about 1 sec per lap compared to solo efforts. So my point is that Clarke's 27:39 is worth about 27:14 under ideal conditions.
Lots of other people ran 27:15-27:30 over the next 25 years after Clarke's WR before the madness began. They all had the benefit of rabbited races and fast tracks.
So it is illogical to just say that Clarke was really a 12:50/26:50 runner who came 20 years before his time.
2) 2nd piece of nonsense:
<<< and we know that EPO or anything like it didn't exist in Clarke's time. >>>
You may not know, but blood-doping existed then, nobody was going to stand up and announce that they were doing it but it certainly was possible during that time (not to mention other drugs). I am not saying that Clarke set WR with drugs, but I AM SAYING that the top times and distances in track and field were set with the benefit of drugs, especially on the women's side. Blood-doping was not illegal then either, it was used in the 1984 Olympic Games by the US Cycling team.
3) Third nonsense:
<<< Or look at the times Henry Rono ran in what was a career that was really abbreviated by his own personal issues. Give him three years in peak form and I think he too would have run times that approach what we're seeing now. >>>
Rono ran the following:
YR Steeple 5000m 10,000m Also
77 nothing nothing 27:37.08
78 8:05.4 13:08.4 27:22.4 27:46,27:48,27:53,27:58
78 steeples- 8:12,8:14,8:15,8:16,8:16,8:17
79 8:17.92 13:19.7
80 nothing 13:19.24 27:31
81 nothing 13:06.20 27:40 (13:12.15,13:12.34,13:12.47)
82 nothing 13:08.97 27:28 (27:29, 27:59)
So that is six year's at the highest level and four WR's anda a top-3 time EVERY YEAR except 1982 when he was #4 in the 5k and #5 in the 10k.
So how is it that he could have run 60 seconds faster than he ever did at 10k and 30 seconds than he ever did at 5k?
It is interesting to not that if you subtract 60 from his WR 27:22 and 30 from his WR 13:08 set the same year, you get 26:22.4 and 12:38.4, almost exactly what Gebrselassie's WR's were.
4) More Nonesense:
<<< As to Mottram, his career progression has been consistent. He hasn't suddenly exploded to a higher level from almost nowhere like Lombard or Regina Jacobs did. His training, from what I've read, has paid attention to his aerobic development which should provide a base for the kind of continuing improvement he's shown. I can't vouch for anyone that I don't know, but I see nothing in Mottram's case to warrant suspicion. >>>
I am not commenting on Mottram because he is NOT what this debate is about, but this statement says that he has been able to progress to 12:55 because "His training ... has paid attention to his aerobic development which should provide a base for the kind of continuing improvement he's shown."
Are you sure that is what you want to go with? Are you saying that all those that have gone before today's runners who run 12:37 and 12:46-12:55 every year, DIDN'T PAY ATTENTION to their "aerobic development" enough to reach faster times?
What do you think the runners of the 70's and 80's were doing every morning? Going to Starbuck's?