We'll, it's possible he has laid off the drugs/partying. It takes more time & energy to take up powerlifting, ontop of MMA training. His body has clearly changed, so the strength & conditioning part, I believe. Training can be an addiction & if it's replacing rec drugs, that's a good thing.
I don't think it will change the douche-like feel of his personality, but it may keep him out of trouble for awhile. That would take therapy & Jones is the type to not actually ever believe he needs therapy.
What's also changed is DC has got 2 hard-won victories under his belt against the next best guys in the division. One problem for him is Jones is still very young & DC is a decade or so older. Things like reach advantage(massive), youthfulness definitely matter in the sport(on top of strength, size & a bit more experience)
I want Daniel to win, but I think if Jones has taken his MMA training seriously, he would be hard to pick against. I disagree that DC would lose to Jones 10/10 times, especially the old one. We will see in the fight though. I feel DC will be mentally stronger & Jones will be physically stronger.