Where should Alberto artificially put the limit on what his people should run? He doesn't know. His educated guess probably is just a bit better than yours. One thing you may be missing is he may say she can run 3:52 and hopes she ends up at 3:55.
I think Alberto's greatest ability as a coach is to get his athletes to believe in themselves. He was the best in the world and he gets his athletes to believe they can be the best. They run way more aggressively than most of the other Americans. Look at Jordan Hasay, She'll die valiantly in races after hanging with the lead as long as possible. And a coach who gets his athletes to believe they can be the best doesn't say, "I only think Mary can run 3:57".
I think the form stuff is overrated except maybe for injury prevention. Mary Cain ran faster than anyone ever before in the high school ranks with pretty poor form.
I enjoyed the article. Got to know a little more about Mary Cain the person. Granted as Robert pointed out with the high school coach and Mary Decker, the author blew it.
With the length of the article I bet it will be in this weekend's Sunday magazine.
92.35% of LetsRun.com voters think the record is dirty from our doping polls
http://www.letsrun.com/data/doping-perceptions-poll/yunxia-qu/so it is pretty common knowledge on here that most people don't believe the record. Interestingly there is only one female record (Jarmila Kratochvílová's 1:53.2 800m) more people thought to be more dirty and that came in at 92.38%.
http://www.letsrun.com/news/2014/02/world-record-results-doping/73.5% of our voters though Slaney was dirty
http://www.letsrun.com/data/doping-perceptions-poll/mary-slaney/