CBD oil has been gaining more and more popularity in the sports world as a way to heal and recover quicker from injuries and general soreness. Smoking or ingesting CBD is also a way to utilize the healing properties of the cannabis plant and pass drug tests, since many companies and leagues (like the UFC) only test for THC.
CDB is only one of 85 active cannabinoids with medical applications found in cannabis. (source: http://www.cbdstore.co/the-nfl-and-cannabidiol)
Leagues with notoriously strict drug polices such as the NFL are beginning to take notice. NFL commissioner Roger Goodell even stated that he would consider allowing the use of medical marijuana if as a neuroprotectant if the science is there to back it up.
For more info on the NFL's use of CBD's click here.
For now cannabis remains banned by pretty much every major sports organization, but with popular athletes such as Diaz becoming spokesman for brands, I believe some progessive leagues such as the UFC will begin to lighten up on their rules as sponsor money becomes more attractive.
Click here for more info on CBD oil.