I still don't think it's outside the realms of possibility
Let me rephrase my comment.
You could be addicted to a drug and play AFL,
BUT you would be lucky to get a kick.
It's been stated on a few other sites that he is the best runner in the AFL and an amazing athlete. We have all seen him play and both WCE supporters and opposition supporters agree the guy is a gun on the football field.
You can't preform at the level he does and be addicted to a drug. If his on-field efforts weren't up to scratch and he got dropped last year, then things would seem very suss.
But he had a great year last year, 553 possessions, 107 marks and 20 goals in 22 games. These are not stats of a person addicted to drugs.
People might come back and say that this happened after the season finished. Again, I don't think you can become addicted to a drug in 3-4 months, maybe heroine, not speed, coke or ecstasy.