Ryan Dunleavypreviews the AFC West as The Post gives division-by-division breakdowns ahead of the 2021 NFL season.

Coach: Andy Reid

2020 record: 14-2

O/U wins: 12.5

Key additions: LT Orlando Brown Jr., G Joe Thuney, RB Jerick McKinnon, C Creed Humphrey, G Trey Smith, G Kyle Long, CB Michael Hughes

Key losses: LT Eric Fisher, RT Mitchell Schwartz, WR Sammy Watkins, CB Bashaud Breeland

First-and-goal: Forced to rely on backups along the offensive line in a Super Bowl loss, the Chiefs didn’t just count on the starters getting healthy. They remade the entire line by signing Thuney, trading for Brown, drafting Humphrey and Smith, letting go of two starting tackles and and bumping former starters such as G Laurent Duvernay-Tardif to the bench. Smart investments when you have Patrick Mahomes, the best QB in the game, throwing to WR Tyreek Hill and TE Travis Kelce. Safety Tyrann Mathieu and DE Chris Jones lead the defense.

Fourth-and-long: It’s Super Bowl-or-bust for the Chiefs while Mahomes is in his prime, which means staying a step ahead of the improving Browns, Ravens, Titans and Bills. After the best pass-catching duo in the NFL, the Chiefs are light on receivers and forced to ask more every down out of former big-play specialists DeMarcus Robinson and Mecole Hardman. DE Frank Clark — an underachiever over two seasons — could be facing an in-season suspension after two arrests on gun charges in a three-month span.

Dunleavy’s Decision: 14-3. Winners of 25 of their last 28 games, the Chiefs will draw every opponent’s best punch again, especially within an improving division.

Coach: Brandon Staley

2020 record: 7-9

O/U wins: 9.5

Key additions: C Corey Linsley, TE Jared Cook, LT Rashawn Slater, OT Matt Feiler, CB Asante Samuel Jr.

Key losses: QB Tyrod Taylor, G Dan Feeney, TE Hunter Henry, G Trai Turner, C Mike Pouncey, CB Casey Hayward, DE Melvin Ingram, S Rayshawn Jenkins

First-and-goal: Justin Herbert looks like the NFL’s next great young QB, which is a must-have to compete with Mahomes’ Chiefs for the next decade. Slater is expected to plug a blindside hole that limited Philip Rivers’ final few seasons with the Chargers and put Herbert at risk as a rookie. Safety Derwin James looked like a future Defensive Player of the Year candidate as a rookie but has played only five games over the last two injury-marred seasons. There’s a lot of star power on both sides of the ball, including DE Joey Bosa and WR Keenan Allen.

Fourth-and-long: Every team is looking for the next young hotshot like Sean McVay, but is Staley — McVay’s former defensive coordinator with the Rams — ready to guide a playoff-ready team to its destination? He was the defensive coordinator at John Carroll University as recently as 2016. CB Chris Harris’ play hasn’t been trending upward, Hayward joined the rival Raiders and pass defense isn’t a good place to have question marks in today’s NFL. The Chargers always seem to have some of the worst injury luck in the NFL. Has the fill-in talent improved?

Dunleavy’s Decision: 11-6. The Chargers check a lot of important boxes with an elite player at QB, WR, DE and safety.

Coach: Vic Fangio

2020 record: 5-11

O/U wins: 8.5

Key additions: QB Teddy Bridgewater, RT Bobby Massie, CB Kyle Fuller, CB Ronald Darby, CB Patrick Surtain II, RB Javonte Williams

Key losses: RB Phillip Lindsay, RT Ja’Wuan James, CB A.J Bouye

First-and-goal: On his fifth team in five seasons, Bridgewater beat out incumbent starter Drew Lock. Von Miller — returning from a season missed due to injury — and Bradley Chubb again could be one of the NFL’s best pass-rushing duos. Actually, this could be one of the five best defenses. The Broncos last reached the playoffs in 2015, when their secondary was a strength. With three new cornerbacks joining S Justin Simmons, that should be the case again. WR Courtland Sutton is another important injury returnee.

Fourth-and-long: In an alternate universe, the Broncos would be Super Bowl contenders because a disgruntled Aaron Rodgers forced his way off the Packers instead of returning for one more season. Alas, that didn’t happen in time for Fangio’s playoffs-or-bust season. The good news: After the Chiefs, the order of finish in this division is a toss-up. The bad news: One team has to finish last. Bridgewater has proven to be fragile, so Lock needs to stay confident and ready. Cutting James after an offseason injury away from the facility opened a hole and rubbed the NFLPA wrong.

Dunleavy’s Decision: 8-9. When you have two QBs, it usually means you have no QB.

Coach: Jon Gruden

2020 record: 8-8

O/U wins: 7.5

Key additions: CB Casey Hayward, RB Kenyan Drake, DE Yannick Ngakoue, DL Solomon Thomas

Key losses: C Rodney Hudson, RT Trent Brown, WR Nelson Agholor, G Gabe Jackson, S Lamarcus Joyner, DT Maliek Collins

First-and-goal: Some of the same proponents of a two-back system were criticizing the Raiders for signing Drake to pair with Josh Jacobs. Both are used to 200 carries plus receptions, so, if they can happily coexist, the Raiders should be able to stay ahead of the chains. Rushing the passer has been a weakness since trading Khalil Mack in 2018, but the smart contract given to Ngakoue should provide a boost. Maybe Thomas, the No. 3-overall draft pick by the 49ers in 2017, benefits from a change of scenery.

Fourth-and-long: The Raiders love to throw curveballs in the first round of the draft. DE Clelin Ferrell and CB Damon Arnette have made the recent gambles look foolish. Will rookie RT Alex Leatherwood — projected as a second- or third-rounder most places — be the next underachiever? After losing three starters on the offensive line, the Raiders can’t afford for Leatherwood to flop. QB Derek Carr, 30, appears to have flatlined in his career. If he is not going to improve, should Marcus Mariota take over?

Dunleavy’s Decision: 6-11. How long can Gruden last in his second stint off the success he had with the Raiders nearly 20 years ago?