ENGLEWOOD, Colo. — Outside of the 100-plus hour work weeks, sleeping at the team’s facility on a regular basis and the crippling stress, having success as an NFL head coach is relatively easy.

Even for a first-time head coach.

But generally, a head coach’s success has less to do about the head coach himself and more to do about one other person in the organization.

The quarterback.

So before calling for Vance Joseph’s job amid the Denver Broncos’ three-game losing streak, understand how crucial a quarterback is to a head coach’s success, specifically a first-time head coach.

The Denver Broncos’ next opponent, the Los Angeles Rams, is a perfect example of this.

Sean McVay took over the Rams’ head coaching job before the 2017 season, much like Joseph did in Denver.

During the 21 regular season games since, McVay’s racked up an incredible 16-5 record — including being only one of two remaining undefeated teams left this year — and has been deemed as the great young mind in the NFL. One of his five losses was a meaningless Week 17 game last year when McVay started backup quarterback Sean Mannion.

In that same time period, Joseph has less than half the wins, going 7-14.

Yet look no further than each coach’s quarterback performance to find out why.

In McVay’s 16 regular season wins, 2016’s No. 1 overall pick Jared Goff has been money — throwing for 37 touchdowns to only eight interceptions for a passer rating well over 100.

In the team’s five losses, however, Goff and Mannion combined to throw only three touchdowns to three interceptions with a passer rating just over 86 in only one of those games.

During the team’s perfect start to 2018, Goff leads the league in passing yards, has 12 touchdowns to only four interceptions and has a 119 passer rating.

Joseph, on the other hand, has not been nearly as fortunate with his signal callers.

Working with a combination of Trevor Siemian, Brock Osweiler, Paxton Lynch and Case Keenum, the Broncos’ quarterback play has been among the worst in the league the past two seasons.

Last year, Denver had the second-worst team passer rating (73), only trailing the Cleveland Browns, who then used the No. 1 overall pick to draft a quarterback.

In the team’s 14 losses since the start of 2017, Denver’s signal callers have thrown half as many touchdowns (11) as they have interceptions (22).

However, in their seven wins, these quarterbacks nearly threw twice as many touchdowns (13) as they did interceptions (7).

In Joseph’s tenure, his quarterbacks have thrown more interceptions (29) than touchdowns (24), making the Broncos only one of two teams to do so in that span. The other, unsurprisingly, is the Browns who now appear to have their future franchise quarterback in Baker Mayfield.

Kyle Shanahan was another first-time head coach that was hired in 2017 — and actually was the runner-up in Denver. Despite the local and national narrative, Shanahan hasn’t been any better than Joseph, racking up an identical 7-14 record.

The only difference between the two is Shanahan has had a competent quarterback, Jimmy Garoppolo, for eight starts, while none of Joseph’s quarterbacks have had more touchdowns than interceptions in his tenure.

Shanahan’s success has come nearly exclusively when Garoppolo’s started.

In Garoppolo’s eight starts, the San Francisco 49ers have gone 6-2 behind Jimmy G’s 12 touchdowns to eight interceptions and a passer rating over 90.

However, when Shanahan hasn’t had the fourth-highest paid quarterback in NFL history, he’s been even less successful than Joseph, going 1-12.

In the 13 games without Garoppolo under Shanahan, the 49ers have 12 touchdowns to 14 interceptions and a passer rating in the mid-70s between C.J. Beathard and Brian Hoyer.

Yet despite being dependent on a quarterback, Shanahan has escaped the level of criticism that’s surrounded Joseph, even though Joseph has had worse play from the most important position on the field.

An argument could certainly be made that these head coaches have had a significant impact on each quarterbacks play.

The counter to that, however, is both the Rams and 49ers each made the biggest investment an organization can make into their respective quarterbacks — Essentially giving each coach the cream of the crop at the most important position in all of sports.

Not only did the Rams use the No. 1 overall pick to select Goff in 2016, they traded two first-round picks, two second-round picks, and two third-round picks in order to move to the top of the draft to take the talented signal caller.

San Francisco traded a second-round pick to acquire Garoppolo in 2017 and then signed him to a then-NFL record 5-year deal worth $27.5 million per season.

On the other hand, Joseph has had to work with a seventh-round pick, Siemian, and a former second-round pick who the rest of the league has deemed a backup, Osweiler.

Joseph was given a first-round quarterback, but the rest of the league is quickly showing Lynch’s lack of success wasn’t due to Joseph, as Paxton remains a free agent after the Broncos cut him in September.

This year, Joseph has Keenum.

However, not only is Keenum’s play not up to par of a top quarterback — or even average — Denver’s investment in him isn’t as monumental as the initial $18 million price-tag would suggest. Only two current non-rookie quarterback starters have a lower salary than Keenum’s $18 million per year average.

While McVay and Shanahan were given the treasure chest for their respective quarterbacks, Joseph has had to deal merely with coins to find his.

The rest of the 2017 first-time head coaching class falls right into place with this trend, too.

Anthony Lynn received a top-10 quarterback performance from Philip Rivers with the Los Angeles Chargers in 2017, and his team’s record reflected it with a 9-7 season.

Sean McDermott, with the Buffalo Bills, received a top-half of the league output from Tyrod Taylor in 2017 and his team finished with a 9-7 record.

History shows it’s simple: Head coaches, specifically first-time head coaches, succeed when they have adequate quarterback play. This is by no means a secret within the Broncos’ organization, either, as one high-ranking member of the Broncos told BSN Denver during the offseason Joseph just needed a quarterback in order to succeed.

Yes, Joseph has been given talent in other areas — i.e., Von Miller and Chris Harris Jr. — but the Rams had just as good of talent with Aaron Donald and Todd Gurley two years before Goff was the full-time starter and McVay joined.

In those two years, the Rams went a combined 11-21 with poor quarterback play. Those two talented players weren’t able to win until they had an excellent quarterback.

This goes well-beyond first-time coaches, too.

Behind every successful long-term coach currently in the NFL, there’s excellent quarterback play behind him.

Bill Belichick, Tom Brady.

Sean Payton, Drew Brees.

Mike Tomlin, Ben Roethlisberger.

Pete Carol, Russell Wilson.

Mike McCarthy, Aaron Rodgers.

Add Sean McVay and Jared Goff to the list soon, if not now.

Joseph, on the other hand, is still waiting for that QB.

Until the Broncos receive adequate quarterback play — whether that be from Keenum, Chad Kelly or a player not currently with the organization — it’s going to be nearly impossible for Joseph, or any head coach for that matter, to find success.