It's strange how quickly opinions can change in the NFL. Take San Diego Chargers wide receiver Keenan Allen for example. Allen burst onto the scene as a rookie in 2013 with 73 receptions for 1,046 yards and eight touchdowns. But he followed that up with a disappointing sophomore campaign in which he managed just 783 yards, four scores and saw his yards-per-catch average dropped to 10.2.

So which player is the real Allen: the electric rookie or the mediocre version that followed? For what it's worth, Allen himself is confident that it's the former and much of that has to do with his new, more serious approach to the game.

"I started to realize how the NFL worked," Allen said to The San Diego Union-Tribune. It may sound cliché or corner or whatever, but (how) you practice (is) how you play, for sure. The work you put in is what you (get) out."

Allen, 23, is no longer the callow rookie he was when the Chargers drafted the then 20-year-old in third round. He's now a father and a trained professional who is doing everything he can to put himself in a position to succeed. Gehlken says Allen played at about 212 pounds last year and slimmed down to 206 this season to ge that extra burst of quickness.

"He's worked hard. It doesn't surprise me one bit with the way he's playing," coach Mike McCoy said after an impressive play from Allen in training camp.

Allen and veteran Stevie Johnson will form the one-two punch at wide receiver for the Chargers. Though they may not be the flashiest names on your fantasy football roster, they bring more than enough to make quarterback Philip Rivers happy.

"The versatility of Keenan and Stevie, if we get to where they're interchangeable from slot to outside and we can move them around, it's going to be huge for us," quarterback Philip Rivers said. "Keenan's a natural in there. He's an X receiver, but I think he may even tell you that may be his most comfortable spot. If they can be interchangeable, that'd be big."

Allen is concerned with improving just one thing, he wants to get better at everything. It's admirable - and possible - given his natural level of talent.

"I don't think I'm going to get in the back and forth game of it," Allen said. "I definitely want to be as consistent as possible. Hopefully, I can have a better season than my rookie season - touchdowns, yards, catches, leading everything. That's definitely my goal."