Barring a last-minute reversal, the Redskins’ receiving corps is going to look a lot different in Washington when the team takes the field in 2017. It also has the potential to be a lot worse.

Last season, the Redskins were third in total offense (6,454 yards), second in passing yards (4,758), second in yards per play 6.4) and fifth in the league in third-down conversions (43.5 percent) — all significant improvements from 2015. According to the game charters at Pro Football Focus, the Redskins had the fourth-most talented group of receivers in the league last year, which helped win eight games without a playoff berth. With DeSean Jackson and Pierre Garcon — each coming off 1,000-yard campaigns — about to move on, the bottom could fall out of the Redskins’ receiving corps.

First you need to consider the hole created by the departures of Garcon and Jackson. Garcon, reportedly set to sign with San Francisco, led the NFL with 113 receptions in 2013 and last season, at age 30, he caught 79 of his 114 targets for 1,041 yards and three touchdowns. Jackson, who led the league in yards per reception two out of his three years in Washington, is expected to sign with the Tampa Bay Buccaneers, removing a potent deep threat from the Redskins roster.

Jackson is one of the premiere deep threats in the league, catching 15 passes for 50 or more yards during his time with Washington (2014 to 2016). That gives him three more than Odell Beckham Jr., who has three more games played and almost twice as many total targets over than span. Plus, quarterback Kirk Cousins’s completion percentage on deep throws, those 20 or more yards, was significantly higher with Jackson in the lineup, as were his yards per attempt and overall passer rating.

What makes Jackson so good as a deep threat is his speed — helping to pull the safeties away from underneath routes — and ability to gain separation from his defenders. According to the NFL’s Next Gen Stats tracking data, Jackson had the second-highest average yards of separation among receivers who saw 100-plus total targets, but fewer than 100 targets when lined up outside. That designation by NFL.com’s Matt Harmon is intended to divide the elite No. 1 receivers from the second tier of talented wideouts. Jackson put 2.9 yards between himself and the defender on passes where he was targeted, and that was even higher when Jackson lined up in the slot (3.3), illustrating how his overall versatility will be hard to replace.

Garcon, who is coming off his first 1,000-yard season since 2013, ranked seventh among that same group of receivers in average yards of separation (2.7), consistently breaking free of defenders when stacked out wide (2.6) or lined up in the slot (2.8). He was also Cousins’ top target in 2016, and Garcon rewarded that trust with just one dropped pass all season.

Those two receivers made Cousins’s job a lot easier. Who will replace them next season?

Absent an addition this offseason, The Post reports that the Redskins will look to move Jamison Crowder, the team’s slot receiver, to the outside but it remains to be seen if he would thrive in that role.

Crowder, a second-year receiver out of Duke who stands just 5-foot-8, caught 67 of his 99 targets for 847 yards and seven touchdowns. More than two-thirds of his routes (398 out of 523) and all of his touchdowns were from the slot, leaving him a mere 229 yards as the team’s boundary receiver. And despite leading all slot receivers in separation (3.6) with a promising split when asked to line up wide (3.9), he ranked ninth overall in yards per route run (1.6) in 2016, significantly behind Jackson and Garcon.

Crowder is a phenomenal asset as a slot receiver, but that could be lost in a role on the outside.

Washington could also experiment with tight end Jordan Reed, but he has shown to work best underneath or in short-yardage situations rather than as a boundary receiver split wide.

Josh Doctson, the Redskins’ top draft pick in 2016, played just two games this season before being shut down with an Achilles issue. As a senior at TCU he caught 78 passes for 1,326 yards and 14 touchdowns, and his size (6-foot-2) allows him to win the ball in the air. But based on his limited reps last season, it would be fair to consider him a first-year receiver and history says success by such players is a crapshoot, even ones drafted in the first round.

Over the last decade, five of the 35 former first-round picks have produced 1,000 or more yards on at least 100 targets: Beckham, Kelvin Benjamin, Amari Cooper, Mike Evans and A.J. Green. If Doctson is going to be the team’s No. 1 or 2 wideout option on the outside, he will have to be at least that good for Washington to not miss Jackson or Garcon.

The other options don’t foster optimism.

Rookie Maurice Harris could get a look, but just three undrafted receivers have topped the 1,000-yard mark in one of their first two seasons. One of those, New York Giants’ Victor Cruz in 2011, lined up in the slot almost three-fourths of the time (72.5 percent).

One visual should put this into a grim perspective: Crowder is the only proven success at the position still on the roster for next season. And the Redskins could be shifting him into a new role. Beyond Crowder? Well, it looks a little something like this.