It is very difficult to catch someone in general. You have to have a suspicion as testing agency and test him for it. There are just so many PED substances. Thats why when you catch someone you have to hammer him for good with lifetime bans or at least some years, otherwise no real scaring of the cheats.
Jones will have cheated most of his time away and will definitely have a new connection on designer stuff. He will not get caught again.
Thats why this is so bad for the sport. Its not only that a lifelong abuser gets encouraged to do it again and for the 10th time gets away with a slap on the wrist, its also an active encouragement to take as much PED as you wish for everyone else. All you need in advance is a way of making yourself the victim (polluted protein) or a fall guy.
These kind of developments reduce my interest in mma more and more. With Jones I am just not interested in seing him again no matter win or loose. Its a bad sign for the future of MMA.