Coghlan's ability indoors seems to have far outstripped his ability outdoors, at least over 1500/mile (I'm not forgetting he won a World Championship 5000m gold).
We're going crazy because Kejelcha got within 0.01 of El G's record, running 3:48.46, but Coghlan ran 3:49.78 nearly 40 years ago no a plywood track, which I've read would be at least a couple of seconds slower over a mile.
Walker had become the first man to run sub 3:50 outdoors only a few years earlier, and here was a guy doing it indoors on a wooden track. And yet he could never even compete with the likes of Coe, Ovett, or Cram outdoors, or even usually Scott, who he demolished in his indoor WR race.
Did he actually try to peak for the indoor season? He was known as the 'king of the boards' and I guess his appearance fee money was greater (once that reputation had been established) in indoor meets than on the European outdoor circuit. Was it his physique that was so ideally suited to the indoor banking? Could he have ran faster in the summer if he hadn't focused on the indoor season picking up cheques?