It (allowing professional athletes to smoke pot)is a tough line to draw. We, obviously, do not want to see them using pre-game as it will effect the on-field product immensely. Allowing it is also a terrible message to youth, who are highly impressionable and look up to these athletes. The current state of legalization in a number of states does, however, create a massive grey area that opens the door to the players unions.
If it were up to me, I would continue with current ban. This is based on societal effects. I smoked habitually for 14 years of my life. I might have it once every 4 months these days and probably less often. Since cutting it out of my day-to-day life, I have turned my business around, my home life is greatly improved and I feel better every second of the day that I don't smoke. Based on this, I feel confident in telling my children that, despite being enjoyable on occasion, marijuana use isn't something that improves your life. It will waste away many days in which you could have been productive. The medicinal effects of THC make it a positive option for many, but employers need to have a cut and dry rule in place. There are effective and legal alternatives and, while playing professional sports, these are the ones the athletes should utilize.
And, Martavis Bryant is an incredible talent who needs to get his head out of his ass. If he didn't get suspended again, I'd look upon it as a miracle.