Your browser does not support the iframe HTML tag. Try viewing this in a modern browser like Chrome, Safari, Firefox or Internet Explorer 9 or later. Marijuana is casting an ever-thickening haze across NFL locker rooms, and it’s not simply because more players are using it. As attitudes toward the drug soften and science slowly teases out marijuana’s possible benefits for concussions and other injuries, the NFL is reaching a critical point in navigating its tenuous relationship with what is recognized as …