After competing just once in each of the last five calendar years, Jon Jones is back to being a fighting champion. His second trip to the Octagon in 2019 takes place at Saturday’s UFC 239, when he steps into the cage opposite Thiago Santos, a 35-year-old Brazilian who is as unlikely a challenger as Jones has had during his brilliant yet turbulent tenure at the vanguard of the UFC light-heavyweight division. This is quite literally true. According to MMA gambling website BestFightOdds, Jones is currently around a -800 favorite against Santos, a number he hasn’t seen since he competed against a fighter who was then seen as a middling contender, Alexander Gustafsson, six years ago.