ESPN released its first 2015 NFL Mock Draft this morning and, unsurprisingly, the last two Heisman Trophy winners are the first two picks off the board. We still have a little ways to go before the draft is officially upon us (April, why are you so far away?). Draft stock could rise and fall between now and then while the order isn't even set in stone yet. But it's never too early to start getting a feel on where the experts think certain high-profile prospects might go.

Here is the top five of the 2015 NFL draft:

1. Marcus Mariota, QB, to Tampa Bay Buccaneers

Mariota just won the Heisman Trophy and is coming off a spectacular regular season. The junior passer accounted for a total of 4,452 yards and 52 touchdowns. That is what I like to call getting it done. Football fans are chomping at the bit to watch Oregon and Florida State in the national semifinals on Jan. 1 to see how Mariota does in a post-season environment. Until then, check out this scouting report form ESPN Draft expert Todd McShay.

"Mariota is a dynamic athlete with excellent top-end speed," McShay wrote. "He is elite at throwing on the run. He has a quick and compact over-the-shoulder release, and he possesses excellent intangibles. The concern I have with him is that while he's good with his anticipation and accuracy when passing from inside the pocket (and he's gotten better at it this season), he isn't great -- and that's the most important quality for QBs transitioning to the NFL level. Is that enough of a risk for the Bucs, a team in serious need of a franchise quarterback, to pass on him? Maybe, or perhaps they would wind up giving Winston a higher grade. But I just can't see either of these guys sliding out of the top 10. This is as shallow of a draft at the QB position as I can remember -- at least in the past several years."

2. Jameis Winston, QB, to Tennessee Titans

You know what there is a constant shortage of? Franchise quarterbacks. Can Winston become that? No one knows just yet. But that doesn't mean the Titans shouldn't try and find out. Winston hasn't lost a game yet in his college career, and Tennessee knows Jake Locker and Zach Mettenberger aren't the long-term answers. Here's what McShay had to say.

"Winston has all the tools to be great on the field as an NFL quarterback. He excels from inside the pocket, has prototypical size, can drive the ball downfield and to the outside hashes, and displays very good game-management skills and on-field leadership. But his off-field behavior to this point frightens me. The Titans and any team that considers drafting him are going to have to be comfortable with what they find when they look into his past, and with his psychological testing. But as I mentioned in the Mariota section, even if one or two teams that need a QB pass on either of these top two QBs, I don't think they all will. It's hard to envision either getting out of the top 10, at this point."

3. Leonard Williams, DE, to Jacksonville Jaguars

Okay, at 2-12 the Jaguars aren't anyone's idea of a model franchise. But they do have certain building blocks in place. Jacksonville is sixth in the NFL in sacks with 38 this season. Williams would be a nice addition to a promising defensive line, especially with current starter Red Bryant on the wrong side of 30. While Jacksonville's offense is in much more need of talent than its defense, passing on Williams' combination of pass rushing and run stopping would be difficult.

"Williams is the No. 1 prospect on our board, with excellent strength and speed for his size, and he'd fit as a 5-technique defensive end in Gus Bradley's scheme."

4. Randy Gregory, DE, to Oakland Raiders

Where to begin? The Raiders could address almost any position with this pick and it wouldn't be a bad selection. They need an infusion of youthful talent and they need it now. Gregory fits that bill. The junior DE racked up 115 tackles and 16.5 sacks during his two years at Nebraska.

"The Raiders need an edge rusher, and the presence of Gregory and [2014 first-rounder] Khalil Mack along the same front seven would create problems for opposing offensive lines for seasons to come...He needs to add strength to succeed in the NFL, as right now he is lean and can get pushed around a bit against the run. But he is a very good pass-rusher with his lateral quickness and closing speed."

5. Shane Ray, DE, to Washington Redskins

A run of defensive ends in the top five. The Redskins are a mess on offense, but at least have some talent scattered about. The defense, meanwhile, could use major upgrades all over. While Washington has been solid against the run this season (only 101 yards allowed per game), they have failed to get after opposing quarterbacks. The Redskins rank in the bottom half in sacks this year.

"The Redskins need a lot of help on defense, and in particular could use a legit pass-rusher with Brian Orakpo unable to stay healthy and Trent Murphy currently starting opposite Ryan Kerrigan. Ray would help immediately...He is an absolutely relentless pass-rusher who is tough, aggressive, can bend the end and has an explosive first step."