many reasons - very few have ever broken 27 for 10K, Galen did. That's pretty significant. In 2012 he came within 1 second of being Olympic champion. His progress is very linear and almost textbook. What you're looking for is a gradual but steady improvement. You don't want to see too much too fast. During the improvement phases you want to see the athlete finish each race with a little left in the tank. By doing so the athlete gains much needed confidence for the next stage. He ran his first sub 60 half and clearly he had reserves. Let's not forget he's a 3:50 miler!!! If I'm Galen I would focus on going sub 59 for the half - sure run Chicago but run no faster than 2:05 range - if he can win at 2:08 or 2:09 that would be even better because the sub 59 is more important at this juncture - then once the sub 59 is achieved then it's a GO for the 2:04's and 2:03's - time will tell if I'm correct. I'm sure Alberto got it down to a science. That's why Alberto gets paid the big bucks.