The tribunal can only make a decision on what is before them - which is TB4.The rules are "to the comfortable satisfaction of the tribunal" or words to that effect. Personally, I trust the tribunal members to make a valid interpretation of that.
Based on Jobe Watson's confession regarding other prohibited drugs, a negative finding by the tribunal will probably not convince me that EFC did not cheat (even though I want closure as much as anyone).
I am also concerned that the penalty might be contrived even if the tribunal find the players guilty. Given the penalties handed out to athletes like Saad, et al, I doubt I would be convinced that anything less than a year of actual suspension (not including backdating, etc) would be reasonable.