I actually expect this is going to be a major letdown fight for many, particularly those expecting some kind of "war." Ponce De Leon isn't really in that many entertaining fights -- he's got good power, but it rarely shows up against top fighters in any big way. They both say they're prepared to go to war, but I mean, this isn't exactly Rios and Alvarado we're talking about here.
Ponce De Leon, at this level, is better off being deliberate and a bit ugly. He's certainly got the thump to stop Mares if he can land a big shot, but his better approach would probably be to mentally frustrate Mares with his odd angles, long reach, and really unorthodox style. Mares has beaten some of the best bantamweights out there -- Perez, Darchinyan, and Agbeko were all top guys, and Moreno, too, though they fought at super bantamweight -- and the move up to featherweight doesn't seem terribly likely to be a major concern, I don't think. Mares is the better boxer, and I think he takes a competitive decision in a totally fine fight that leaves a lot of folks disappointed because there's not blood flying anywhere, unless we get some headbutts. Mares by decision.
This could either be a very good scrap, or a painful foul-fest (literally). I'm kind of leaning toward the latter. I hope I'm wrong, but I think Ponce De Leon will try to jab from the outside and hold Mares when he gets too close. When Mares does get close he will make it ugly as well, hitting Ponce De Leon on every body part he can find. I have a feeling the early rounds will be relatively uneventful as Ponce De Leon tries to setup a jab and work from the outside. As the fight moves forward and Mares get more desperate to make it a brawl, he will foul and it could get ugly. Nevertheless, he knows that kind of fight favors him, and referees have not been overly quick to deduct much from him. Mares will take over down the stretch with his aggression, and take a close, controversial decision. Mares by decision.
The big question in this match-up will be how Mares handles fighting in the featherweight division. Whilst Ponce De Leon isn't the tallest featherweight around, he is broad across the shoulders and looks the more natural featherweight. Ponce De Leon is a dangerous puncher but there's a big gap between the pair in terms of ability, Mares is levels above his fellow Mexican, who is at best crude, flat-footed and slow.
It seems simple enough for Mares - if he can avoid Ponce De Leon's bombs, he should be able to effortlessly take the fight on points. Mares wide UD.