The Serby Mock 3.0, selections 1-20, operates on the theory that the Vikings will beat the Jets, Broncos and Cardinals to prospective $30 million man Kirk Cousins.

This will be the last mock before the start of free agency.

Sam Darnold, QB, USC

Draft day. Can’t afford to pick a Bo Callahan. No Mistake By the Lake this time. Hue Jackson is the right man to develop him behind, say, AJ McCarron … as long as he can win a damn game by Halloween this time.

Josh Allen, QB, Wyoming

With the Giants on the clock, GM Dave Gettleman answers a war-room call from an old friend.

“I learned real early that, number one, you have to get the quarterback when you have a chance,” Ernie Accorsi reminds him.

Missiles at the Meadowlands. Big hands, big arm. He’ll sit behind Eli Manning (and Davis Webb) while Pat Shurmur and Mike Shula develop him.

Josh Rosen, QB, UCLA

A trade based on two possibilities: 1) John Elway is fearful of the Jets trading up for this quarterback; 2) Colts GM Chris Ballard has Saquon Barkley and Bradley Chubb rated equally.

Saquon Barkley, RB, Penn State

GM John Dorsey thought about making this game-changing thoroughbred the first overall pick, and the great Jim Brown is ecstatic.

Bradley Chubb, DE, N.C. State

If anyone ever needed an elite 6-foot-4, 285-pound pass rusher to chase Deshaun Watson and Marcus Mariota (Blake Bortles, not so much), it’s new coach Frank Reich.

Baker Mayfield, QB, Oklahoma

A heated war-room debate over whether to draft Lamar Jackson instead is solved by Christopher Johnson, who frantically summons Christian Hackenberg from the cold tub to flip a coin — heads for Broadway Baker, tails for Broadway Lamar. Heads it is. Bill Polian pans the pick, believing Broadway Baker is shorter than Doug Flutie. Moxie in the Meadowlands. Let him learn how to be a pro under Josh McCown.

Quenton Nelson, G, Notre Dame

Doug Martin can only wish he could have run behind this 6-foot-5, 325-pound road grader who may be able to play tackle, too. A nasty plug-and-play bodyguard for Jameis Winston. “Good golly,” Gettleman tells reporters, “that is one fine Hog Mollie.”

Minkah Fitzpatrick, CB, Alabama

Prince Amukamara is a free agent, and Aaron Rodgers and Matthew Stafford — and possibly Cousins — will be on the schedule twice.

Joshua Jackson, CB, Iowa

A big corner is needed opposite Ahkello Witherspoon if Trumaine Johnson signs with the Raiders. Denzel Ward is barely taller than Bill Polian.

Derwin James, S, Florida State

A Gruden Grinder who can match up with Travis Kelce and Hunter Henry.

Tremaine Edmunds, LB, Virginia Tech

Adam Gase might need this freakish 6-foot-5, 250-pound replacement for Lawrence Timmons.

Lamar Jackson, QB, Louisville

Marvin Lewis buys himself another decade of job security.

Denzel Ward, CB, Ohio State

Kendall Fuller was dispatched to the Chiefs in the Alex Smith trade, Josh Norman is 30 and Odell Beckham Jr. will be returning.

Roquan Smith, LB, Georgia

New GM Brian Gutekunst stays true to the board with an infusion of new blood for thirtysomething linebackers Clay Matthews and Ahmad Brooks.

Calvin Ridley, WR, Alabama

With uncertainty surrounding Dez Bryant, Jerry Jones leapfrogs the Ravens for the draft’s best wideout.

Mike McGlinchey, OT, Notre Dame

Ozzie Newsome plugs a hole on the right side instead of reaching for a wide receiver.

Vita Vea, DT, Washington

A 340-pound dancing bear to discourage Marshawn Lynch and Kareem Hunt.

Da’Ron Payne, DT, Alabama

Michael Bennett and Sheldon Richardson could be goners.

Mason Rudolph, QB, Oklahoma State

Rookie coach Steve Wilks has a desperate need with Carson Palmer retired.

Isaiah Wynn, G/T, Georgia

Rookie coach Matt Patricia stalks a running back next.