It's actually YOU and Ziggurat who has burnt all credibility.
The 1650 is in YARDS, not METRES.
You are right, I screwed up. I had looked into this issue quite some time ago and had remembered that there were inequivalencies that weren't being taken into account, but did not remember the details, and I jumped on what looked like an inconsistency which is actually pretty small. So I was wrong.
But I don't think you've got a full handle on the issue either. You said Ledecky's record for 1650 yards was 15:03.92. And yet, her Wikipedia page lists her 2013 World Championship 1500 meter time of 15:36.53 as being a world record. Why the discrepancy? Why was a significantly slower time a world record, rather than the faster time?
The answer is pretty simple, and it's what I forgot the details of. Her 15:03.92 time was in a
25-yard pool, her World Championship record was in a
50 meter pool. 66 laps of a small pool vs. 30 laps in a larger pool. The smaller pool times will be significantly faster than the larger pool times (despite being slightly father), because you can gain a lot of speed on each kickoff. So you cannot compare large pool and small pool times as being equivalent. Not only do you need to specify the length of the swim, you need to specify the size of the pool.
OK, what about Thomas's 15:59.71 time? It was held at
Ocasek Natatorium, which has a 50 meter pool. So his time is more comparable to Ledecky's 15:36.53 time than her 15:03.92 time. Still behind, though, right? Yes, but the thing is, that
isn't Thomas's best 1650 time. Thomas's actual best 1650 time is 14:54.76, which beats either of Ledecky's times. I'm having a hard time finding out if this was a small pool or a large pool, but either way Thomas was still faster than Ledecky.