A year ago, Hayden, the Raiders' top pick of the 2013 draft, was not only still recuperating from the near-fatal heart injury that ended his college career early, but he was also recovering from a follow-up surgery to clear out resultant scar tissue.
"I'm great, I'm feeling a whole lot better," Hayden said last week after the Raiders' first organized team activity. "I've been lifting (weights), working out, and I actually got a full offseason in so I'm ready. I'm ready for the season to start.
"(Last year), in the OTAs, because seeing all my teammates out there working out and I'm hooked up to IVs, it might mess up anybody's head a little bit, but I'm way over that now."
The Raiders have just as much, if not more, confidence in Hayden as the team gathers today for an open-to-the-media practice to kick off Week 2 of the three-week, 10-practice OTAs.
Even if, after having a short-circuited beginning to his rookie season, Hayden's year came to a premature close with a trip to injured reserve after just eight games due to a groin injury.
You get the sense the Raiders want Hayden to claim the right cornerback position, with newly-signed Tarell Brown locking it down on the left side and Carlos Rogers coming in to cover the slot receiver in nickel situations.
"I think he's light years ahead of where he was at this point last year," Raiders coach Dennis Allen said of Hayden. "Not just from a physical standpoint, but really from a mental standpoint too. I think he realizes now that everything's going to be fine, he's going to be OK, and now he can really focus on getting better as a football player.
"I like what I've seen out of D.J. so far. (He) still has a lot of things to learn, (he's) still kind of a quasi-rookie out there, but I'm looking forward to his development and I think there are some good things in store for him."
In fact, it's as if Hayden is a "bonus" draft pick for the Raiders, one with half-a-season of NFL experience, including two starts, and an interception already under his belt.
"Well, I mean, he's not necessarily starting on ground zero like most of these rookies are so he's got a little bit of a head start, but yet he still has a lot of room to grow," Allen said. "There was a reason why we took him where we took him last year. We feel great about the player and we're excited to see how he can develop (from) last year."
Hayden had a "burn rate" of 60.6 last season, per Stats, Inc., giving up 23 receptions on 38 targets for 386 yards and three touchdowns. And the last time he was on the field, against the Philadelphia Eagles, Hayden surrendered 139 yards and two TDs on three catches, two to Riley Cooper and one to DeSean Jackson.
Hayden acknowledged, though, that being mentally healthy now might be more important than his physical well being.
"It really is because, if you know what to do, your natural reaction is you're just going to do it," Hayden said. "You're already athletic enough to do it; you just have to do it."