THAT SAID, I believe it's time for the NFL to consider doing away with testing and suspensions for weed, it's legal in 2 states now, reports are that weed use amongst NFL payers is widespread and positive tests are easily avoided because they are warned before a test. It's medical benefits for pain management is real and well documented which is a big benefit to players who are pretty much injured all the time, and weed use does not cause people to do the stupid kinds of things that alcohol does, which is perfectly legal. The legalization in CO and WA have not resulted in mayhem as many had predicted, quite the opposite.
I don't smoke weed, but many of my friends do, and my whole life I've had friends who did, and I can personally attest from observation that weed is nowhere near the destructive substance that alcohol is. And I am by no means anti-alcohol.
On the flip side, tar from marijuana is damaging to the lungs which can negatively affect a player's athletic performance, and those who live on the edge will often get high, then get drunk, and what follows can be a total mess. People who smoke can easily conceal it, so players might come to practice stoned, meetings stoned, and lose their edge if they get addicted. But they might be doing it already if it's as widespread as reported.
Ultimately however, it boils down to $$$. If you're suspending big time names such as Gordon and Von Miller, you're losing $$, period, which is the biggest reason the NFL would have for considering letting players get high, would it make them more money?
Good article that written by someone much smarter than I: http://www.washingtonpost.com/opinions/the-nfl-should-let-its-players-smoke-pot/2014/01/10/d97f5c56-7710-11e3-af7f-13bf0e9965f6_story.html