It's anecdotal evidence vs. information sourced from the game data.
Possible and probable are two very different things. All the players whose 15Air or 15Playful regularly gets beaten down by high level Champs can attest to that. Battling is all about odds and probability, and the best chance of winning any battle is to use the dragon most likely to win. The odds aren't wrong, the sample size you are using for comparison is too small.