Mock 21-Final Edition is my set-in-stone projection on the first 21 picks in Thursday night's draft, and who the Detroit Lions will draft with pick No. 21.

The Lions are picking five spots lower than last year, when general manager Bob Quinn took offensive tackle Taylor Decker of Ohio State 16th overall in what turned out to be a successful draft that helped build a solid foundation.

There's enough talent available this year at a variety of positions – defensive line, running back, receiver, tight end, pass-rush specialist – to add starting help and reserve depth to the Lions' roster.

"It's really a well-rounded draft at all levels," Quinn said at his pre-draft press conference. "We think there are guys that we think can help our football team.

"There's depth at positions we're looking at."

Hint on my Lions pick: In my first three mocks I picked a defensive player from the University of Michigan -- defensive end Taco Charlton in the first two, and safety Jabrill Peppers in Mock 21-3.0.

I'm sticking with a U. of M. player.

Here is the Mock 21-Final Edition breakdown: Rules for the Mock are no trade projections; a quote from Quinn; defense dominates the top 10; the run on running backs is surprising; the Lions' position at No. 21 gives them flexibility – to trade or pick from a handful of good prospects, plus set themselves up for Rounds 2 and 3 Friday, and a final thought.

Quinn's quote: He has a 'best-player-available" philosophy, but with a qualifier.

"Best player available – meshing with what the needs are on your team," Quinn said at his pre-draft presser. "You have to look at both avenues (need and talent) when making decisions. Not just the first round -- all throughout the draft."

1. Cleveland Browns (1-15): Coaches want the elite defensive player. Analytics department wants the QB – and gets one later.

Pick:DE Myles Garrett, Texas A&M.

2. San Francisco 49ers (2-14): They're likely to get offers to trade down.

Pick:DE Solomon Thomas, Stanford.

3. Chicago Bears (3-13): The top safety is tempting, but building up front has been a priority elsewhere for head coach John Fox, and this one can play on the edge or interior.

Pick:DL Jonathan Allen, Alabama.

4. Jacksonville Jaguars (3-13): Same school from my previous mocks, but different player. Forget a QB. As head coach of the Jags from 1995-2002, Tom Coughlin drafted three QBs and none higher than the third round. Blake Bortles gets another year to prove he can lead a franchise that has won 17 games in the last five seasons – the same total the Patriots won last season, including playoffs.

Pick:RB Leonard Fournette, LSU.

5. Tennessee Titans (from LA Rams 4-12): Jacksonville's pick shifts choice from cornerback to safety.

Pick:S Jamal Adams, LSU.

6. NY Jets (5-11): Upside for a QB trumps having only 13 starts in college, and the Jets aren't ready to win, anyway. Take the QB.

Pick: QB Mitchell Trubisky, North Carolina State.

7. LA Chargers (5-11): Talent fills need – a natural fit for the D.

Pick: S Malik Hooker, Ohio State.

8. Carolina Panthers (6-10): Fournette could have been the pick to fill a big hole, but the Panthers might get a more versatile back to give Cam Newton options in the backfield.

Pick:RB Christian McCaffrey, Stanford.

9. Cincinnati Bengals (6-9-1): Another change from my previous mocks because of how the final board falls. Teams are flexible. So am I. Maybe it's the mental yoga.

Pick:CB Marshon Lattimore, Ohio State.

10. Buffalo Bills (7-9): Another target for QB Tyrod Taylor. Since they brought him back, it makes sense.

Pick:WR Mike Williams, Clemson.

11. New Orleans Saints (7-9): It's imperative to add talent to a defense that's mostly responsible for three straight 7-9 seasons. This could have been Reuben Foster's spot. His character issue is another player's gain. I moved Foster out of the top 21.

Pick:LB Haason Reddick, Temple.

12. Cleveland Browns (from Eagles 7-9): It's a good spot to take a quarterback. I'd take the winner – Deshaun Watson of Clemson – but the buzz is that the Browns' eyes are on Texas.

Pick:QB Patrick Mahomes II, Texas Tech.

13. Arizona Cardinals (7-8-1): The pick for the future would be a QB to succeed Carson Palmer, but defense in 2017 comes first.

Pick:DE Derek Barnett, Tennessee.

14. Philadelphia Eagles (from Minnesota Vikings 8-8): A cornerback on the rise jumps ahead of Florida's Quincy Wilson.

Pick:CB Gareon Conley, Ohio State.

15. Indianapolis Colts (8-8): A running back is a QB's best friend. Andrew Luck, meet your new best friend.

Pick:RB Dalvin Cook, Florida State.

16. Baltimore Ravens (8-8): GM Ozzie Newsome is one of the NFL's top talent evaluators. He was a Hall of Fame tight end. He knows quality.

Pick:TE O.J. Howard, Alabama.

17. Washington Redskins (8-7-1): Speedy playmaker fills the role once held by DeSean Jackson.

Pick:John Ross, Washington.

18. Tennessee Titans (9-7): Two ways to go – WR or TE – will make QB Marcus Mariota happy.

Pick:WR Corey Davis, Western Michigan.

19. Tampa Bay Buccaneers (9-7): McCaffrey's versatility would have been an ideal fit, but Jameis Winston can't feel bad about getting another athletic target.

Pick:TE David Njoku, Miami (Fla.).

20. Denver Broncos (9-7): It makes sense to protect the QB – whoever it is.

Pick:OT Ryan Ramczyk, Wisconsin.

21. Detroit Lions (9-7): As promised, my pick for the Lions is a defensive player from U. of M. But it's the U. of M. in Columbia, Mo., not Ann Arbor.

Pick: DE Charles Harris, Missouri.

Here's my first-round pick breakdown:

1. The case for Harris: It's no knock on Taco Charlton or Jabrill Peppers that I'm taking Harris over those two.

At 6-3 and 253 pounds, Harris does not have the height and length of Charlton, who measured 6-6, 277 at the Combine. But Harris is quicker off the edge, and showed more explosiveness in the agility and jumping drills. Those skills translate to getting to the quarterback.

As former NFL GM Charley Casserley said in a podcast on WJR-760, Harris rates ahead of Charlton in his ability to sustain his quickness to defeat blockers.

Harris' stats: A three-year player at Missouri, he had 30.5 tackles for loss his last two years, with 16 sacks.

Harris vs. Charlton, Peppers: Charlton would be a good pick for the Lions, and they should be happy to have him if that's what they decide, but Harris would be better.

As for Peppers, the curiosity of what he'll do at the next level is probably the most of any player on the board.

Peppers is a tremendous athlete who played across the board in his two full seasons at Michigan.  He'll help some NFL team immediately returning kicks and punts, but the question of where he fits best is a real issue when drafting a player in the top two thirds of the first round.

Trade possibilities: With so many players with similar grades available at No. 21, the Lions are in good position to deal. Most likely it would be down. Three teams to watch because of the possibility of getting in position to take a quarterback are the Texans at 25, Saints at 32 and Browns at 33, if they don't take a QB at 12.

Other rounds: Linebacker and running back are positions the Lions could look at, and there's depth on the defensive line with a number of players who are edge rushers -- either defensive end in a 4-3 or outside linebacker in a 3-4.

Players to consider: Takkarist McKinley of UCLA, Tim Williams of Alabama and T.J. Watt of Wisconsin are highly regarded prospects who would be versatile in the front seven.

At linebacker, Jarrad Davis of Florida, Zach Cuningham of Vanderbilt, Raekwon McMillan of Ohio State, Kendell Beckwith of LSU, Duke Riley of LSU and Tyus Bowers of Houston are promising linebackers – inside and outside.

Depth at running back is higher than in most years. Alvin Kamara of Tennessee, Samaje Perine of Oklahoma, Kareem Hunt of Toledo, D'Onta Foreman of Texas, Marlon Mack of South Florida and Matt Dayes of North Carolina State all could be second-day picks – second and third round – who'll help a team either as a lead back or as a rotation or specialty back.

Final thought: It cannot be stressed enough that it is not a one-round draft. Drafting reliable, consistent players who fit a team's scheme is as important – and often more so – as taking a prospect whose athleticism is off the chart.

The spotlight shines brightest on the first round on prime-time TV, but rosters are built by grinding through all seven rounds, plus culling the crop of free agents who are not one of the 253 players drafted.