By far my biggest disappointment of the year: stars (particularly American ones) ducking competition.
Coleman and Holloway using their wildcard entries to dodge some fascinating races at US Champs. Mu shutting it down post Eugene, McLaughlin pulling out of races last moment/dipping Monaco to run in Hungary then shutting it down.
Rai Benjamin shutting it down after Eugene. Man has done 5 Diamond League 400m hurdles in the last 5 years. I get the DL can be hard to fit with an American schedule but of those 5, 2 were in Doha and one was in Shanghai - the two most inconvenient Diamond Leagues to hit (and ones that offer the biggest appearance fees).
McLaughlin, Mu, Benjamin, - they're all fascinating and talented athletes who I'd love to see more.
I'd add as a specific disappointment- men's 110m hurdles final. All year I wanted Holloway v Parchment v Cunningham v Allen. To lose both Parchment and Allen sucked.