Reyes' left counter is his money punch, he counters moving backwards well.
If you watch Reyes vs Volkan he doesn't look like a man who is ready to fight and beat Jones, that fight really sticks out like a sore thumb, but Volkan has shown an improved game and is dangerous with his power. It's possible the fight looked as close as it did because Reyes was just determined to stick to the gameplan. Small mistakes against Volkan have got a lot of people knocked out. You take that fight away and Reyes has looked very good.
It's possible we are seeing Jones off drugs his past few fights, possibly for the first time in his career. The current narrative is that Jones is slowing down and doesn't look as good as he did. One thing I have noticed is recently Jones has wrestled much less, in his last 4 fights he has totalled 4 takedowns, 3 of those against Smith. It's possible that a Jones off of drugs doesn't have the cardio to maintain a high pressure, high pace, wrestling game over five rounds. Why not take Santos down? It was the obvious path, the least dangerous path, but even when Santos was injured Jones still chose to stand and just pick away.
Could very well just be a choice Jones made in the moment or it could be that Jones knew if he went for takedowns and failed he would tire.
If Jones doesn't or can't wrestle, for whatever reason, and has a kickboxing match with Reyes, does he win that fight?
I don't think Reyes has the gas tank for five rounds either, if he has to defend takedowns, but without a wrestling element he can stand and trade for the full five and I think he would have the advantage there.