Frankie Edgar is an incredible fighter. His resume at Lightweight is undeniable. Not only has he put together an awesome streak of fights against some of the best in the sport in one of the toughest weight divisions in the UFC, he's doing it when that tough division isn't even his natural home. The loss to Benson Henderson has many calling for him to drop to 145 lbs, something he can easily make. But why? Will he find more success there? I don't think he would, because the champ at Featherweight is scary good. But it's also important to note how you define success.
Jose Aldo is an animal. He destroys wrestleboxers in his sleep, and has faced quite a long list of them. The only trouble Aldo has faced in recent memory was the fifth round of his fight against Mark Hominik. A worn down, completely sick Aldo managed to destroy Hominik for four rounds before succumbing to an early takedown in the fifth. Instead of trying to make something happen, Aldo was perfectly content to take a breather, clearly ahead on scorecards, and didn't even attempt to get up and instead opted to take Hominik's decent ground strikes.
Back to defining success. I think Edgar definitely has what it takes to beat just about everyone at Lightweight and even win that title back with some evolution to his game. Edgar's wrestling is absolutely incredible. There were times when he effortlessly tossed the much bigger Henderson to the ground, sometimes not even wanting to follow him there. He already holds wins over Miller and Maynard. He is a stylistic nightmare for Nate Diaz. I'd pick him in a fight vs Anthony Pettis, and the fight vs Henderson was close. If Edgar capitalized on some of the takedowns he was managing to get against Henderson, the end results could've been much different. While it would be really, really tough to get the belt back, I think it's better than the destroyer of worlds that would await him at 145. If you define success as "ability to win and hold the championship belt" then Lightweight is the better option. If you don't, Kenny Florian is one of the most successful fighters in the world.
Take a gander at the top Featherweights in the UFC. Hioki, Mendes, Poirier, Nunes, Korean Zombie, Hominik, Palaszewski, Gamburyan. Frankie Edgar destroys those fighters. He wins with ease in just about all of them. But then look at Mr. Aldo Jr. Aldo blends his quick, powerful striking with excellent takedown defense. Frankie would be able to land some takedowns, but Aldo has an awesome ability to pop right back to his feet, where he has a significant advantage over Edgar, more so than any fighter Edgar has ever faced. But really the main point of why Frankie shouldn't drop to 145 dwarfs any of my other arguments: dropping to 145 doesn't solve his problem of being smaller than his opponents. Aldo his huge. He has a difficult time cutting weight, so much so that many people urge him to move up to Lightweight. Dropping to 145 to face the Champ only takes away the speed advantage he has at Lightweight while not offering very many positives, since he's at a size disadvantage, a power disadvantage, and speed is relatively close. Frankie takes tons of punishment, and Aldo has an ability to land a blow that sends you to the edge of consciousness and then follows up with such a barrage of strikes that ends any ideas of getting back to your feet. Aldo has the best stylistic advantage over Edgar than anyone at 155 or 145.
As long as Aldo reigns at 145, Edgar should take his chances with Henderson/Pettis/Miller/Diaz/Guida. I'd sooner want to see him cut the 20 pounds to make Bantamweight and take Cruz's belt than see him in the Octagon against Aldo.