Everything about last year’s Broncos offense was tough to watch.

They cycled through quarterbacks like they had an expiration date, turned the ball over more than any team except Cleveland and did not have a 1,000-yard receiver for the first time since 2011.

But if the Broncos are to go from worst to first in the AFC West this year, their red-zone offensive production will be critical.

It must be better. And, really, it can’t get much worse.

The Broncos’ red-zone offense was first in 2013 and fourth in 2014, scoring touchdowns on 76.1 and 62.9 percent of their opportunities with quarterback Peyton Manning at the top of his game. But the touchdown efficiency decline has been startling — 28th in 2015 (47.7 percent; they still won the Super Bowl), 26th in 2016 (46.8) and last in 2017 (39.6 percent).

In just five years, the Broncos have sunk from first in points per red-zone possession (5.87) to last (3.83).

But new offensive coordinator Bill Musgrave should have several reasons to be encouraged: the signing of quarterback Case Keenum, the draft of a physical tailback — Royce Freeman — who can pound for valuable real estate, the debut of tight end Jake Butt and the arrival of second-round receiver Courtland Sutton.

Better players could make Musgrave’s red zone play-calling sing.

“Any time you have better players, your red zone offense looks better,” said tight ends coach Geep Chryst, who has coordinated offenses in San Diego and San Francisco. “We like the additions we made this offseason but we need to work on it so we’re working on it.”

Red-zone periods were a constant during the open training camp practices in August. The Broncos needed to get all of their young players (Sutton, Freeman, Butt and receiver DaeSean Hamilton) up to speed with that part of the playbook. Related Articles Broncos Briefs: After fine, Vic Fangio vows to be more aware of wearing mask

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Sutton knows how to use his 6-foot-4 frame to win in the air, making him a perfect option for red-zone fade routes, which should open up quick slants for Demaryius Thomas and Emmanuel Sanders.

“(Sutton’s) a big body with great ball skills,” coach Vance Joseph said. “He has strong hands so even when the ball is contested, he can win. Hopefully he’s over 50 percent (on the 50-50 passes). That would be huge for us, especially in the red zone.”

Close to the 20-yard line, Butt and tight end Jeff Heuerman had success beating linebackers down the right and left seam, a big-time asset in the red zone.

The challenge for Butt, Chyrst said is, “where are those little air pockets in the defense? And then (against man coverage), you try to win the 1-on-1 matchup because you’re not going to get 1-on-none in the red zone.”

During a two-point conversion play against Chicago last month, Heuerman used a double move to easily beat his opponent and catch Keenum’s pass.

Freeman isn’t afraid of contact so he could be the goal-line option — he scored on a four-yard against the Bears and looked comfortable in tight confines.

It all starts with Keenum, though. He knows how to force the football to a receiver without being careless. He knows how to extend the play, rolling right or left while keeping his eyes up for the receiver who leaks open.

Last year for Minnesota, Keenum had 16 red-zone touchdown passes and no interceptions. The Vikings’ 112.1 red-zone passing rating was second in the league; the Broncos were 29th (79.5).

Last year, the Broncos started 7 of 9 in the red zone in wins over the Chargers and Dallas to start the season. But then followed a stretch of 2 of 12 that helped derail the season. Over their final six games, Denver scored only four touchdowns in 15 red-zone possessions.

Staying on schedule was the usual culprit. Take December’s win over the New York Jets. The Broncos went 1 of 4 in the red zone. Their three non-touchdown possessions:

First down: Three-yard check down pass. Second down: Two-yard check down pass. Third down: Incompletion into double coverage.

First down: Bad throw incompletion. Second down: Four-yard run despite having three tight ends in the game to block. Third down: Three-yard pass.

First down: No gain run. Second down: Sack. Third down: Four-yard run.

The playmakers didn’t get open or their quarterback was inaccurate, indecisive or both or the offensive line didn’t open a hole. The Broncos ranked last in yards per red-zone play (2.09) and 16th in red-zone third down chances (38.5 percent).

In this year’s preseason, Musgrave presented multiple personnel combinations and formations during red-zone trips against Chicago.

From the Bears 18, the Broncos ran one receiver/two back/two tight ends and threw to fullback Andy Janovich in the flat. On the next play, they had three receivers to the left and motioned tailback Phillip Lindsay out of the backfield and to the left; he caught a short pass that was negated by a penalty. Later in the game, Musgrave motioned tight end Matt LaCosse to Sutton’s side. That created confusion among two Bears defensive backs. They both followed LaCosse, freeing up Sutton for a 16-yard touchdown catch.

The Broncos are Musgrave’s fifth NFL coordinator spot. In his eight years as a coordinator, Musgrave’s offenses have finished in the top half of the league three times — ninth with Minnesota in 2011 (56.6), 14th in 2015 (57.1) and ninth in 2016 (61.0) with Oakland.

“Red zone is important because if we do a good job there, there is a huge difference between seven and three,” Musgrave said. “We’ve got strides to make in that area so let’s put the time on task to get better.”