at plus 1500 joppy is def a bet to consider and Taylor is NOT on the same level talent wise as Cotto ( is in my opinon the outstanding talent in boxing today)
What i have seen of taylor (which is not much) he is tall and has a good jab which let him dictat the fight, such fighters look always good against reluctant opponents who fight defensively and dont attack at close range and try to stay close. Wladimir Klitschko absolutly dominated his opponents with monster jab.
Joppy was in with good opposition and hang in there with Hopkins for 12 painful rounds and he has a win over Eastman who is a quality fighter.
Scenario Joppy is successful at pressuring Taylor and getting close and Taylor cant handle the situation and cant infight and feels lost when you take away his jab.
This is not a quality analysis because i have seen a half fight of Taylor and two of joppy, but thats the beauty of betting huge dogs you win big and lose little and all you need is not totaly absurd scenario.
Gil this is def. a better bet than betting guys like Rahman at - 800 against Cole,
although you probably will lose with Joppy but it a solid bet and the odds are to high.
Good luck