Your response initiates a few questions --
1) Do you honestly believe a 3:51.59 miler could only run 52/1:50 or do you just think that these numbers make better fodder for your calculator?
What 3:35/3:51y performer in history was only able to run 52/1:50?
He ran 1:49.80 in '81, while he was in college. In the years that followed he concentrated on training and ran better and did not run the 800. Clearly he improved in 1982, then '83, then '84, then '85 and '86.
Your calculator is worthless ... useless.
The only value it has at all is as a trolling tool.
In Chrono order --
1500m
3:37.96 Jack Buckner GBR 22.09.61 2 Tirrenia 25.08.1982
3:37.25 Jack Buckner GBR 22.09.61 7 Koblenz 31.08.1983
3:37.66 Jack Buckner GBR 22.09.61 3 Bruxelles 01.07.1984
3:37.32 Jack Buckner GBR 22.09.61 6 Rieti 02.09.1984
3:36.73 Jack Buckner GBR 22.09.61 8 Oslo 27.06.1985
3:35.28 Jack Buckner GBR 22.09.61 3 Stockholm 01.07.1986
Mile
3:53.44 Jack Buckner GBR 22.09.61 8 Cork 13.07.1982
3:55.91 Jack Buckner GBR 22.09.61 6 Edinburgh 31.07.1982
3:59.48 Jack Buckner GBR 22.09.61 6 London 20.08.1982
3:56.79 Jack Buckner GBR 22.09.61 4 Gateshead 10.06.1984
3:56.27 Jack Buckner GBR 22.09.61 5 Cork 03.07.1984
3:51.57 Jack Buckner GBR 22.09.61 4 Koblenz 29.08.1984
3:58.07 Jack Buckner GBR 22.09.61 2 Inglewood 08.02.1985
3:55.61 Jack Buckner GBR 22.09.61 3 Westwood 18.05.1985
3:57.29 Jack Buckner GBR 22.09.61 6 London 08.08.1986
3:59.33 Jack Buckner GBR 22.09.61 4 Birmingham 19.08.1986
3:59.55 Jack Buckner GBR 22.09.61 4 London 22.08.1987
3:58.87 Tom Buckner GBR 16.04.63 8 Portsmouth 05.06.1993
2) What is "generic" about Buckner? He was a Euro Champion and 3rd place in the WC. He would be equal to a 12:52-55 runner who medaled in a WC meet in this era.
The point of my obscenely long post was to point out the flaws in your approach. It is your calculator that is broken. I think that part of how it is warped is that it doesn't take into account the effects of EPO (which affects the 3k/5k/10k more than the 800/1500).
When Buckner ran 13:10 / 7:40 (in the SAME YEAR) he was 9.75 secs and 8.33 secs off the WR for 5k and 3k respectively. Those results are pretty comparable if you ask me.
So the upshot is ... If Keino could run 3:26, then Buckner could have run 12:50. I am just illuminating the absurdity of the calculator that you use.
These runners from Buckner's era, and before the EPO era, have real world marks that show the flaw in your approach--
Hutchings --
7:43, 7:44, 7:44, 7:44, 7:45+, 7:46, 7:46, 7:47, 7:48+, 7:49, 7:49 (no indoor marks)
13:11, 13:12, 13:16, 13:19, 13:20, 13:20, 13:20, 13:23, 13:23, 13:24, 13:24, 13:24, 13:24, 13:25, 13:25, 13:25, 13:26, 13:26, 13:27, 13:28, 13:29, 13:29, 13:29 (no indoor marks)
Others --
Ovett -- 7:41, 7:43, 7:44 / 13:20, 13:23, 13:24
Walker -- 7:37, 7:40, 7:41 / 13:19, 13:20, 13:24
Treacy -- 7:45, 7:47, 7:47 / 13:16, 13:19, 13:20
Plasencia -- 7:46, 7:47, 7:49 / 13:19, 13:19, 13:23
McChesney -- 7:40, 7:45, 7:48 / 13:14, 13:15, 13:18, 13:19
Is the calculator that you use online?