INDIANAPOLIS - The 2018 season unofficially kicks off this week as the entire NFL descends upon Indianapolis for the Scouting Combine. Free agency is just around the corner, but hundreds of draft prospects will be put under the microscope as decision-makers try to sort through who they will or won't pick in April's NFL Draft. On Friday, the offensive linemen and running backs take to the turf at Lucas Oil Stadium to prove themselves in athletic testing drills. Who should you be watching? Let's take a closer look.

Top Pick

This is the player at each position who I feel is at the top of the class coming into the event, and who should hear his name called first among the position in April.

Offensive Line: Quenton Nelson (Notre Dame)

I would argue that Nelson is the best overall player, regardless of position, in this draft class. I don't think he will be the top pick, but he is as close to "can't miss" as it gets. The junior left guard started for three years for the Irish, and his combination of size, strength, movement, toughness, and intelligence make him as polished an offensive lineman as we've seen in some time coming out of school. His workmanlike attitude away from the field will leave teams smitten.

Running Back: Saquon Barkley (Penn State)

If Nelson isn't the best player in the draft, the argument can be made that Barkley is. The physical freak show from Penn State went to high school just north of Allentown, Pennsylvania and was a three-year starter for the Nittany Lions. An explosive runner with game-breaking potential both as a ball carrier as well as a receiver and kick returner, Barkley is almost certainly a lock for the top 10 selections of the draft. He should be a day one starter in the NFL. Not only is he the best back in this draft, but I expect him to post some jaw-dropping test scores in the athletic drills on Friday.

Workout Warrior

This is the player at each position who I expect to see perform best in the athletic testing portion of the workout (40-yard dash, cone drills, jumps, and/or bench press).

Offensive Line: James Daniels (Iowa)

A two-year starter for the Hawkeyes at center after spending his freshman year at guard, James Daniels is a very impressive athlete for the position. I believe that Daniels can be a catalyst for an NFL offense up front similarly to how the Eagles use Jason Kelce out in space. Daniels' movement skills will almost certainly land him in the top 50 picks of this draft. Other names to watch for in these athletic tests are West Georgia's Desmond Harrison, UCLA's Kolton Miller, Pitt's Brian O'Neill, Army's Brett Toth, and Virginia Tech's Wyatt Teller.

Running Back: Nyheim Hines (N.C. State)

A first-team All-ACC pick this year as a junior, Hines has been a standout on the track for the Wolfpack as well throughout his college career and has been considered one of the fastest players in college football the last two years. I expect him to post the top 40-yard dash of any running back and rank as one of the top testers overall this weekend. In my mind, Hines transitions in a similar way as Washington Redskins' Chris Thompson, though I've spoken with some draft experts who see some shades of former Eagle Brian Westbrook as well. The former receiver has some warts to his game (drops as a receiver and his overall lack of size to work between the tackles), but he's a very intriguing player in the middle rounds as we sit here today. I also expect USC's Ronald Jones to run very well on Friday, while LSU's Derrius Guice and Arizona State's Kalen Ballage should post some of the best numbers overall for the position as well.

Trust The Tape

This is the player at each position who I don't expect to test off the charts and is a better football player than he is an athlete. With that in mind, don't drop him down the board with a subpar workout!

Offensive Line: Tyrell Crosby (Oregon)

Tyrell Crosby is one of a handful of offensive tackles in this class who is viewed as a likely second-day selection who could slide into the back end of round one. My guess is that it won't be his athleticism that puts him over the hump and into the top 32 picks. A grinder at the point of attack and one of the best run blockers in this class, Crosby has an NFL frame, can move people up front, and has a good idea of how to use his hands. Even if he posts an average workout, I'm not worried about his future. I don't expect Oklahoma's left tackle, Orlando Brown, to test well on Friday, and I'd be shocked if Clemson guard Taylor Hearn posted better-than-above-average numbers as well.

Running Back: Nick Chubb (Georgia)

Coming out of high school, Nick Chubb was viewed as one of the best athletes in the entire country. A devastating knee injury in 2015 has people wondering if he's the same kind of athlete, however, and it has led some analysts to like his teammate Sony Michel a little bit more as the draft approaches. It's entirely possible that Chubb surprises us with his workout. Either way, I'm not worried about the senior ball carrier, whose game is based more on vision, toughness, and instincts than burst and lateral agility. I'd put Auburn running back Kerryon Johnson on this list as well.

Stopwatch Shocker

This is the player at each position who I expect to see test better than most in the media believe based off of current projections.

Offensive Line: Isaiah Wynn (Georgia)

Wynn has started for the last three years for the Bulldogs, but this was his first year at left tackle after spending the previous two inside at left guard. A short, compact blocker who thrived last month at the Senior Bowl in everything he was asked to do, Wynn isn't necessarily known for his athleticism, but I'd be willing to bet that he posts a pretty surprising workout (in a positive way) on Friday morning. A tough, battle-tested, versatile linemen with good tape and good workout numbers? Yeah, those types don't typically last long on draft weekend. I expect Mike McGlinchey from Notre Dame and David Bright from Stanford to also post better athletic scores than most think.

Running Back: Justin Crawford (West Virginia)

My first inclination for this category would be to go with Kalen Ballage from Arizona State, a 220-pound back who I believe will test very well and be one of the talks of the running back position coming out of the Combine. To me, however, that's low hanging fruit. I'm going to reach a bit deeper here and go with Justin Crawford, a senior runner from the Mountaineers who proved in 2016 to be a game-breaking threat in the wide-open Big 12 Conference. A creative runner with sneaky vision, deceptive speed in the open field, and a bit of a mean streak as a ball carrier, I think Crawford will run well on the track and earn himself a bump in his overall stock when it comes to his draft buzz. Small school runner Roc Thomas from Jacksonville State, a former five-star recruit from Auburn, will also surprise people with his times on Friday.

Will Kill The Drills

This is the player at each position who may or may not be a great athlete, but he will look the best in the position-specific drills after the athletic portion of the workout.

Offensive Line: Austin Corbett (Nevada)

A college tackle who will almost certainly have to slide inside to guard or center in the NFL, I watched Corbett and came away thinking he was one of the most technically sound linemen in this class. An above-average athlete who looks comfortable on the move, Corbett uses his hands well and just looks the part as an interior blocker. I think he will definitely impress in position drills, where the fluid athletes usually stand out above the rest. I'd also throw Texas' Connor Williams and Auburn's Braden Smith into this bag as well.

Running Back: John Kelly (Tennessee)

Stuck in the shadow of Alvin Kamara in 2016, John Kelly took the reins in the Tennessee backfield for most of this season and showed why he's one of the best backs in the country. He's not as explosive an athlete as his former teammate but is a tough, competitive runner who excels at making the first man miss. He also catches the ball extremely well, which will show up on the turf during positional drills. Kelly may not be a future starter, but I think he'll stick in the league for a long time as long as everything is squared away off the field.

Most To Prove

This is the player at each position who has the most to prove away from the field, whether it's during the interview process, medical examinations, or even the weigh-ins.

Offensive Line: Will Richardson (N.C. State)

Watching Richardson on film, you see a player who has the look of a starting NFL lineman. He's got a good looking frame, heavy hands, and the strength to move people seemingly at will in the run game with feet to match. The junior was suspended twice in three years, however, and will have questions to answer for some decisions he's made off the field. Interviews will be key for him this week.

Running Back: Ronald Jones (USC)

He doesn't have the off-field concerns and injuries were not an issue for Jones during his career. The question he has to answer has to do with his frame. At 6-0, 215 pounds for the Trojans, there are questions about the junior's ability to carry a heavy workload in the NFL. Will he be able to handle the rigors of a 16-game schedule as a primary ball carrier? Similar questions were asked of Jamaal Charles coming out of Texas a few years ago, and he ended up having a very nice career but physically broke down a bit quicker than people hoped. If Jones can maintain that speed we've seen on film for the last two years, he'll likely be a top-50 pick.

Most Productive College Player

This is the player at each position who produced at the highest level, either in his final year in college or over the course of his entire career.

Offensive Line: Billy Price (Ohio State)

Unlike every other position in football, there are no universal stats for us to follow with offensive linemen to track productivity. They say, however, that there is no better ability than availability, and Price started a school-record 55 games for the Buckeyes during his four-year career. How impressive is that number? By my records, no offensive lineman drafted in the last decade had more than 53. A three-year starter at right guard who slid inside to center as a senior, Price won the Rimington Award this year as the nation's best center, was a two-time All-American, and a two-time, first-team All-Big Ten player. Ironically, Price suffered an injury during the bench press on Thursday and his status is unknown moving forward.

Running Back: Rashaad Penny (San Diego State)

Penny began his career as a three-year backup behind Eagles 2017 fourth-round pick Donnel Pumphrey, the most productive back in college football history. How did Penny follow that up? He led the nation in rushing yards as a senior (2,248) and scored 23 touchdowns on the ground as an All-American and first-team All-Mountain West selection. Penny added four more touchdowns as a receiver and on special teams. He has been one of the top kick returners in the country over the course of his career as well, scoring seven total touchdowns on special teams. A decisive back with elusive traits, third-down potential, and the size to be an every-down ball carrier, it was a crime that Penny didn't finish as a Heisman finalist. My guess is he'll be hearing his name called on day two of the NFL Draft.

Best Pro Comparison

Comparing draft prospects to NFL players is tough, but here's a player with the easiest picture to paint when looking at his NFL future through my eyes.

Offensive Line: Cole Madison (Washington State)

Coming up with a player comparison can be very tough sometimes. It's never easy to find an NFL player who a prospect reminds you of in so many ways from a physical, schematic, and play-style standpoint. With Madison, however, it was very easy. From the jump, he reminded me of Green Bay Packers left tackle David Bakhtiari with his body type, quickness, and play personality. Like Bakhtiari coming out of Colorado, I think Madison deserves a shot on the outside as a tackle, where he was a four-year starter for the Cougars. He could very easily transition inside as a guard in the NFL.

Running Back: Kalen Ballage (Arizona State)

This is going to seem a bit outlandish, and I hate comparing a prospect to one of the best players in the NFL at any position, but Ballage has a lot of similar traits to Pro Bowl running back David Johnson, particularly coming out of Northern Iowa. Johnson was a size/speed runner from a small school who had really impressive athleticism for a big kid and was at his best as a pass catcher out of the backfield. The same could be said for Ballage, who never really put it all together as a runner and was part of a committee with fellow senior and Combine attendee Demario Richard throughout his career. Both Johnson and Ballage had questions about their vision entering the NFL, and while Ballage is certainly no sure thing, if he lands with a coaching staff that can best leverage his skill set he could be one of the steals of the draft.

Small-School Standout

This is the player at each position who comes from a lower level of competition but still has a very bright future in the NFL.

Offensive Line: Alex Cappa (Humboldt State)

One of the darlings of the NFL Draft, the Division II lineman from a school that hasn't had a player drafted in over 25 years will be one of the stories to watch this week. Cappa was an early standout at the Senior Bowl in January. His highlight reel is one of the most impressive you'll watch of any lineman entering the draft. However, his damage was done at a much lower level of competition compared to what he'll see next year in the pro ranks. How will Cappa fare? Teams are hoping to get an idea of that this week. Don't be surprised if ends up in the second or third round of the draft.

Running Back: Chase Edmonds (Fordham)

A four-year starter for the Rams, Edmonds was one of the most productive players at the FCS level entering the year before injuries hampered his senior season. Still, the Harrisburg, Pennsylvania native made quite a name for himself, and transitions well as a rotational piece in an NFL backfield similar to how James White has carved out a role for the New England Patriots. A scrappy runner who catches the ball well, can make the first man miss, and rarely put the ball on the ground, Edmonds is a name to watch in a deep running back group.

Philly Connection

This is the player at each position with a special tie to the City of Brotherly Love or to the Eagles that you should keep a close eye on.

Offensive Line: Mike McGlinchey (Notre Dame)

In a tackle class that has every analyst under the sun fighting for who is at the top of the heap, my pick would be the senior from Notre Dame. McGlinchey, who is a Philadelphia native and went to Penn Charter High School, where his cousin Matt Ryan graduated from, has NFL size, good feet, and the ability to move people in the run game. He's the most well-rounded tackle in the last two drafts, in my opinion, and should be the first one off the board. Time will tell if it works out that way, and he's far from a perfect prospect (I'd like to see him get stronger in his upper body), but the Philly kid and three-year starter is my favorite tackle in this year's class.

Running Back: Josh Adams (Notre Dame)

McGlinchey's former teammate isn't from the City of Philadelphia but grew up just outside in Warrington, a suburb in Montgomery County. At 6-2, 225 pounds, the junior captain has NFL size, impressive straight-line speed, and he should test pretty well in some key categories. He's not the most natural runner of the football right now, and I'm not sure that he'll be viewed as a primary ball carrier at any point in his career. However, he's got NFL ability, is young, has plenty of tread left on the tires, and can impact the game in a number of ways. Adams is an impressive prospect.

Mr. Average

We get to read all about the measurements for all these players over the next few weeks ... but wouldn't it be nice to have some context? What is considered a "good" 40-yard dash time for any given position? What about arm length? The broad jump? Here's what the average player drafted at each position has looked like over the last decade (by my records).