2018 NFL combine primer: Kiper, McShay answer biggest questions

The NFL combine -- the most important evaluation event on the road to the 2018 NFL draft -- is here, and all the best prospects are in Indianapolis to show their stuff in front of NFL front-office personnel.

With workouts starting Friday -- here's the full schedule -- we asked ESPN NFL draft experts Mel Kiper Jr. and Todd McShay to break down what they'll have their eyes on in Indy, from the top quarterback prospects to potential fallers and risers, and more.

Click the links below to go to each section:

Top QB watch | Biggest questions | Filling in the blanks

McShay: What I'm looking for from the top six QBs

Sam Darnold, USC

Scouts Inc. position rank: No. 1

For Darnold, I'll be monitoring the little things in Indianapolis. His hand size, for one. Ball security has been an issue (14 lost fumbles in 24 starts), but that could be partly due to his mechanics as well. He's not throwing in Indianapolis, but we'll be able to see him go through athletic testing. And no, I'm not overly concerned by him not throwing. Darnold was a three-sport athlete in high school and went 20-4 at USC with a supporting cast that wasn't as amazing as some people think. His decision to not throw at the combine will have no impact on whether a team decides to draft him (or any QB).

Josh Rosen, UCLA

Scouts Inc. position rank: No. 2

The interview process is going to be far more important than anything Rosen does on the field. Teams will have a psychologist in the room studying his answers and body language on a variety of topics from his coachability, love of the game and more. Is he a good teammate and leader? Does he need the game? It will all come out during these interviews and private visits with teams.

Josh Allen, Wyoming

Scouts Inc. position rank: No. 3

We all know that Allen can spin it with the best of them, so I'll be focused on his footwork. Is he continuing to tighten it up in three- and five-step drops? He needs to be more consistent with his base and weight transfer. I'll also be looking to see how he fares on touch throws in drills.

Baker Mayfield, Oklahoma

Scouts Inc. position rank: No. 4

Mayfield has plenty of experience at QB, so I'm more interested in the interviews for him as well. Does he love the game, or does he love what the game brings him? I've always been extremely impressed with Mayfield's ability to lead his team, and I'm guessing he wins over every room he's in this week.

Lamar Jackson, Louisville

Scouts Inc. position rank: No. 5

Jackson probably has the most to prove out of any of these quarterbacks. How well does he retain information in interviews on the chalkboard? Has he been tightening up his mechanics? When he misses, he tends to miss high because of a stiff front leg and inconsistent drive and follow through. And finally, is he gaining good weight that he needs to survive in the NFL? Jackson has a lot of questions to answer.

Mason Rudolph, Oklahoma State

Scouts Inc. position rank: No. 6

I'm focused on Rudolph's football intelligence in interviews, particularly when he's put on the chalkboard, and his agility. He has a good frame and impressive arm, but he lumbers a bit in his pocket movement at times. I want to see how he performs when he's forced to throw the ball on the move.

Kiper & McShay: Answering the biggest combine questions

Who are the prospects with the most to gain at the combine?

McShay: I'm going to highlight four guys here. I love the tape of South Dakota State tight end Dallas Goedert. He's my top-rated prospect at the position and the rare two-way tight end with impact pass-catching skills and the ability to block. I'm hearing he could run in the 4.5s in the 40-yard dash and put up impressive numbers across the board. It's an important week for him after an injury at the Senior Bowl.

I'm also keeping an eye on Boise State linebacker Leighton Vander Esch, Alabama safety Ronnie Harrison and Arizona State running back Kalen Ballage. A really good workout could catapult Vander Esch into Day 1 contention, and the versatile 'backer should put up strong numbers in drills. Harrison has been overshadowed by Alabama's other top prospects, so this is a good showcase to see whether he has the athleticism to rise into the first round. Ballage is a big 6-foot-2, 222-pound back who had an impressive week at the Senior Bowl. In a loaded class of running backs, could a great workout move him into Day 2?

What about the prospects with the most to lose?

Kiper: Iowa cornerback Josh Jackson burst onto the scene in 2017 with eight interceptions, and he's my No. 2-ranked corner. But there are questions about his long speed, and his 40 time is critical. He could drop if he doesn't run in the 4.4s. Two underclassmen at offensive tackle, UCLA's Kolton Miller and Pitt's Brian O'Neill, have great feet, but how strong are they? O'Neill didn't have a great week at the Senior Bowl, struggling in one-on-ones. I thought Ohio State defensive end Sam Hubbard might have a dominant 2017 season, but he was inconsistent before coming on in the final three games. Does he have the athleticism to play on his feet, or is he strictly an end in a 4-3 scheme? If he doesn't test well, he could drop.

Which prospects could run the fastest 40-yard dash?

McShay: There are several burners in this class, but I'm going to go with Ohio State cornerback Denzel Ward. One of the most explosive athletes to come out of Columbus in the Urban Meyer era, he's very twitchy and just as fluid as he is fast. He can lock down the top CB spot with a great workout, and possibly go among the top 10 picks.

Kiper: My two guys to watch: LSU cornerback Donte Jackson, and NC State running back Nyheim Hines. Both ran track in college, are extremely explosive and could contribute in the NFL in the return game. Jackson is on the fringe of the first round and could rise, while Hines is probably a Day 2 pick.

Who will be the No. 1 workout warrior?

McShay: It's tough to go against Virginia Tech linebacker Tremaine Edmunds, who's a 6-5, 250-pound physical specimen. He can rush off the edge, cover tight ends and play on or off the line of scrimmage, and he had 102 tackles last season. According to the folks I've spoken to in Blacksburg, Edmunds is going to light up the combine. He went No. 10 in my Mock Draft 2.0, but he could rise even higher.

Kiper: Edmunds is getting a lot of buzz, but here's another guy to keep an eye on: Florida defensive tackle Taven Bryan. He didn't have a dominant 2017 -- he had six tackles for loss and 40 total tackles with only four sacks -- but he's a total freak at 6-4, 291. He's still raw, but he has all the physical attributes to be a star. Penn State running back Saquon Barkley, a likely top-five pick, is also expected to test extremely well.

Which prospect's medical report will you be most intrigued to hear about?

Kiper: Josh Rosen is the big one. The UCLA quarterback had a shoulder issue that forced him to miss several games in 2016, and he dealt with two concussions last season. Does he have any lingering effects? His interviews with teams are going to be the most talked about of any prospect. Florida State safety Derwin James missed almost all of the 2016 season because of a knee injury and wasn't the same player in 2017. He's a super-talented kid who could rise or fall based on his medical.

McShay: Alabama linebacker Rashaan Evans is a top-20 talent, but a scary groin injury early in the season -- he said muscle was ripped from the bone -- has teams wanting to take a closer look. Running backs Nick Chubb (Georgia) and Bo Scarbrough (Alabama) both had significant leg injuries in college, and how they check out and perform in drills will go a long way in their rankings.

Kiper: Filling in the blanks on the combine

_________ is the pass-rusher I'm most excited to see in workouts.

Lorenzo Carter. He was used in different positions at Georgia and wasn't always asked to rush the passer -- he had only 9.5 sacks over the past two seasons. But at 6-6, 242, Carter has the frame and athleticism to blow up at the combine. I'm told he could run in the 4.5s in the 40. He's the type of raw prospect NFL coaches will draft high and try to mold into a supreme pass-rusher, and he could rise into the first round with a stellar workout.

The receiver who could rise (or fall) based on his 40 time is _________.

Courtland Sutton.The SMU wideout has fantastic size at 6-4, 215, and he had 22 touchdown catches over the past two seasons. But will he show quickness and explosion? Scouts are keeping a close eye on him as a possible late-first-round pick in a weak receiving class.

One hybrid linebacker to keep an eye on is _________.

Uchenna Nwosu. At 6-3, 240, I'm not sure the USC defender can be an every-down player, but he is a fantastic and aggressive edge rusher. He was unblockable down the stretch of the 2017 season, racking up eight sacks over his final six games. Nwosu is probably a third-round pick at this point, but his stock could rise at the combine.

The best comp for pass-rusher Bradley Chubb is _________.

Cameron Wake. The longtime Dolphins defensive end has had a fantastic career after going undrafted in 2005. He had to put on weight in the CFL before getting a shot in the NFL, where he has made five Pro Bowls and has 92 career sacks. Both are hard-nosed players with similar size. Chubb, far and away the best edge rusher in this class, is a prototypical 4-3 end. It will be tough for him to move up in the draft because he's already likely to be a top-three pick.

_________ is an under-the-radar skill-position player who will be a star.

Kalen Ballage. Todd mentioned the Arizona State running back earlier, but Ballage is another candidate for combine workout warrior. I expect him to test extremely well.

The best nickel corner in this class is _________.

This is a tough one. I'm going to cheat a little bit because this kid could play outside some, too. Louisville's Jaire Alexander could be a star in the slot. He had five interceptions (and a punt return touchdown) in 2016 but played only six games last season because of injuries, and he's only 5-11, 190. Alexander is probably a second- or third-round pick at this point, but he has the quickness to excel as a nickel corner.