It has been a whirlwind last couple months for Detroit's 21 rookies, and they are about to embark on the most import three-week job interview of their lives.

Training camp is a grind even for veteran players, but it's especially true for the NFL's newest crop of players. Roster spots and playing time are on the line, and some NFL dreams will come to a temporary end.

Following rookie minicamp, 10 OTA practices and a mandatory minicamp, coaches should expect the rookies to hit the ground running when camp begins. Those that don't will be left behind.

So where do the rookies stand heading into training camp?

Jarrad Davis, LB, first-round pick: Davis has stepped into the MIKE linebacker role from the first day he got to Allen Park, and is already calling the defense. He's still learning Teryl Austin's scheme, but he's very smart and instinctive, and brings a speed and power element to the middle of the defense. He'll enter camp as the starter at the MIKE with the first-team defense.

Teez Tabor, CB, second-round pick: Concern about Tabor's speed didn't appear to be a factor in the open portion of OTAs and minicamp. Tabor ran with Detroit's receivers, and even found a way to make a few plays. We'll see the true scope of his game when the pads come on and he can start being physical with receivers at the line of scrimmage and in the five-yard buffer zone. He'll certainly be in the mix for playing time.

Kenny Golladay, WR, third-round pick: Golladay's been one of the more impressive rookies throughout the offseason training program. He's a big target at 6-foot-4, and has shown to have a nice pair of hands. He seemed to make at least one big play in every open practice.

Jalen Reeves-Maybin, LB, fourth-round pick: His speed and ability to cover jumped out this offseason. There is going to be stiff competition for playing time at the WILL linebacker spot, but Reeves-Maybin has as good a shot at earning playing time there as anyone else. How quickly he picks up the scheme, which will allow him to play fast, will determine his role. At the very least, his speed could make him a good cover man on special teams.

Michael Roberts, TE, fourth-round pick: Playing tight end in the NFL is tough business. It's rare that a rookie comes in and makes a huge impact. Even players like Vernon Davis, Jason Witten and Jimmy Graham made marginal contributions as rookies. Learning to play all the different roles a tight ends has to play, along with all the blocking schemes he's responsible for, takes time. It was the same for Eric Ebron back in 2014. Roberts is the third tight end behind Ebron and Darren Fells, and will likely see his biggest contributions come in the red zone early on.

Jamal Agnew, CB, fifth-round pick: It's a crowded cornerback room right now, and the competition will be fierce for playing time. That should make everyone better by the end of camp. Agnew's 4.3 speed stands out. He could push Quandre Diggs for time in the slot. He's also thrown his hat into the return man competition. If he impresses there, it might be his fastest way onto the field.

Jeremiah Ledbetter, DT, sixth-round pick: The six-game suspension levied to Khyri Thornton has pushed everyone behind him up a spot in the rotation. The Lions kept five defensive tackles on the 53-man roster out of camp last season. Haloti Ngata and A'Shawn Robinson are in. That leaves Ledbetter competing with veterans Akeem Spence, Jordan Hill, Ego Ferguson, Bruce Gaston and Thornton for two or three spots.

Brad Kaaya, QB, sixth-round pick: The Lions have kept two quarterbacks on the opening week roster the last couple seasons. Kaaya will battle Jake Rudock to be Matthew Stafford's backup in camp. Kaaya has a lot of upside, but Rudock's knowledge and comfort in Jim Bob Cooter's scheme gives him a significant edge at this point. Kaaya will have a chance to earn the job just like Rudock did last year before he eventually lost out to Dan Orlovsky and began the season on the practice squad.

Pat O'Connor, DE, seventh-round pick: It's hard to evaluate edge rushers when there's no pads and just light contact in the offseason workouts. O'Connor proved to be a playmaker in college (forced seven fumbles over last two years). He'll have to make plays to stand out in a veteran defensive end group that includes Ziggy Ansah, Kerry Hyder Jr., Cornelius Washington, Armonty Bryant, Anthony Zettel and Brandon Copeland.

Brandon Barnes, TE, undrafted: The top three tight end spots are well established with Ebron, Fells and Roberts. The Lions could decide to keep four tight ends on the initial 53-man roster as they did last year. If that's the case, Barnes, Cole Wick, Khari Lee and fellow undrafted tight end Robert Tonyan will be competing for one roster spot and one of the 10 practice-squad spots.

Alex Barrett, DE, undrafted: Barrett racked up 40 career tackles for loss and 19 sacks as an All-Mountain West performer at San Diego State. It's a crowded group at defensive tackle, but there's always room for undrafted players who come out and prove they're playmakers in the preseason.

Dontez Ford, WR, undrafted: The competition for the remaining receiver spots are wide open, which is good news for the trio of undrafted receivers on the roster. Jace Billingsley earned a spot on the practice squad last year, in large part, because of his performance in the preseason. He eventually earned a roster spot at the end of the year. Ford must have the same approach: Make plays and see where it takes him.

Tion Green, RB, undrafted: The fullback position is no longer a part of Detroit's offense, which could leave the door open for the team to keep a fifth running back on the initial roster. The current pecking order at running back is Ameer Abdullah, Theo Riddick, Zach Zenner, Dwayne Washington, Mike James, Matt Asiata and then Green. If the Lions keep five, the competition between James, Asiata and Green will be one to watch in camp.

Leo Koloamatangi, C, undrafted: It's going to be tough for Koloamatangi to crack the roster as an interior offensive lineman because of the terrific veteran depth the Lions have there. That doesn't mean it can't be done. Koloamatangi has terrific size and strength, and he'll have a chance like everyone else to make the most of his reps. T.J. Lang, Graham Glasgow, Travis Swanson, Joe Dahl and Laken Tomlinson are currently ahead of him on the depth chart.

Desmond Lawrence, CB, undrafted: Lawrence has terrific length at 6-foot-1. That can't be taught. The competition for the two starting spots alongside Darius Slay and pecking order behind them is wide open. If he impresses early on, he'll get a look like everyone else.

Storm Norton, T, undrafted: Taylor Decker's shoulder injury could potentially open a roster spot at tackle if he misses any time in the regular season. Rick Wagner is locked in at right tackle. It will be an uphill battle for Norton, who will have to beat out established veterans Greg Robinson, Cyrus Kouandjio, Corey Robinson, Cornelius Lucas and Tony Hills for a spot.

Michael Rector, WR, undrafted: Like Ford, Rector will get an opportunity to impress and make a play for one of the roster spots behind Marvin Jones Jr., Golden Tate and Golladay. His 4.42 speed will have to be the difference maker for him. Making plays down the field will go a long way to earning a role, even if it's on the practice squad.

Noel Thomas, WR, undrafted: Thomas isn't big (6-0, 205) or fast (4.63), but he was one of the most reliable receivers in college football last season. He caught 100 passes for 1,179 yards. He has terrific ball skills, and that could set him apart from his fellow undrafted rookie receivers.

Josh Thornton, CB, undrafted: Thornton was a small-school prospect (Southern Utah), who some thought would be a late-round pick. He had a knack for the ball in college, and will have to show the same knack at this level if he wants to earn a spot on the roster or practice squad.

Robert Tonyan, TE, undrafted: Tonyan is in the same boat as Barnes. It's a pretty established group of tight ends in Detroit, but players can always force a coach's hand by making plays. Tonyan ran a 4.58 40-yard dash at his pro day with a 35-inch vertical leap at 6-foot-5 and 200 pounds. He's a converted wide receiver.

Jeremiah Valoaga, DE, undrafted: Valoaga missed some time in the offseason with an undisclosed injury. He's an athletic edge rusher with ideal size and length. Like Barrett and O'Connor, Valoaga will have to navigate through a crowded group of veterans at the position.