"the time convergences between SCM and LCM in distance events may suggest more room for improvement in underwater performances in mid distance and distance races. In shorter events, the difference between SCM and LCM may reflect the modern focus on underwater training, as many coaches and swimmers have rightly regarded turns and underwaters as separate events unto themselves".
Underwater turns have been around for over 20+ years now, and have been perfected by virtually every top swimmer in competition. Do you really think that all the 800/1500 swimmers just did not notice this going on, and their coaches have been keeping these turns a secret from them? There is no doubt in my mind, that the metabolic cost of these turns is just too prohibitive for the long distance events, and net times slow down if you pay that cost off the walls. That is why "NO ONE" does them in these races, not because they have not tried. You can talk about arms getting tired, or legs, but overall in a distance event, it is your basic fitness and ability to maintain an on the top of the water pace that gets you to the finish line as quickly as possible. These guys suggestion that it is just a coaching or training oversight, that they do not take advantage of the new style turns, well it is just ignorant of what actually is going on..