March 8th, 2016, was supposed to be a dark day for Matthew Stafford. That's when his star receiver, Calvin Johnson, announced his retirement from the Detroit Lions.

Stafford had made his living by being a high-volume, gun-slinging, risk-taking passer who leaned on Johnson's exploits to prop up his own raw stats. With Johnson out of the picture, Stafford was supposed to struggle in 2016.

Instead, he's having what is easily the best season of his career.

Stafford has gone from a volume-dependent free spirit to a high-efficiency fiend who has led his team to three consecutive come-from-behind victories. Even without Johnson and high volume, Stafford has risen to a new level as a passer, and it's time that we take notice of what he's doing.

We can quantify all of this using numberFire's Net Expected Points (NEP), the metric we use to track a player's efficiency. There's a big difference between a 3-yard completion on 3rd-and-2 and that same 3-yard completion on 3rd-and-4, and NEP helps flesh that out by tracking the expected points a player adds to or subtracts from his team's total on a given play.

Let's use NEP to dig deeper into Stafford and show why 2016 has been the best version of him we have ever seen.

Failure to Meet Expectations

As the first overall pick back in 2009, it's easy to understand why Stafford would be entering the league with gigantic expectations. He was joining a team that had gone winless the season before and had endured countless failures at quarterback leading up to that pick. Stafford couldn't sniff living up to those expectations early on.

The table below shows how Stafford fared in two crucial categories the first six seasons in the league in which he recorded at least 200 dropbacks (he did not hit this mark in 2010 due to injury). The first is Passing NEP per drop back, which divides the total expected points the player added through the air by their number of drop backs (pass attempts plus sacks). Success Rate is the percentage of drop backs that result in positive NEP. As you can see by his yearly rankings in those categories, although he wasn't bad, he wasn't quite what you want out of such a high draft pick.

Outside of a surge in 2011, Stafford has largely just been average. For some perspective, since Stafford entered the league, Philip Rivers has as many top-five finishes in Passing NEP per drop back (three) as Stafford has top-15 finishes. Stafford wasn't hurting the Lions, but he really wasn't helping them much, either.

This year has been a radically different story. Through seven weeks, Stafford ranks 4th in Passing NEP per drop back of the 32 quarterbacks with at least 100 drop backs, and he is 7th in Success Rate. He's in line to pick up his first ever top-five finish in Passing NEP per drop back, and this comes the season after he loses one of the best wide receivers of all time.

The question here is obviously, "How?" Most of the credit thus far has gone to offensive coordinator Jim Bob Cooter, who took over in that role prior to Week 8 of last year. It's easy to see why when you compare Stafford after the switch to what he had done before..

Over the final nine games of 2015 -- the time period in which Cooter was the offensive coordinator -- Stafford's Passing NEP per drop back was 0.18. This is a far cry from his mark of 0.00 prior to that, so Cooter obviously deserves some of the credit. But even that falls short of the sauciness Stafford has unleashed this year.

Instead of last year's mark of 0.18 with Cooter, Stafford has pumped up his Passing NEP per drop back all the way to 0.30 in 2016. The league-average mark has gone up to 0.14 from 0.11, which certainly plays a role in Stafford's improvement, but it can't account for all of it. Neither can Cooter's presence. At the end of the day, it's Stafford who deserves a majority of the credit for his improvements, even if they do highly correlate with Cooter's promotion.

Conclusions

The odds were stacked against Stafford entering the season without his crutch in Johnson, but he has lived up to the task and become a whole new player.

Stafford's efficiency marks through the first seven games are the best in his career, following four straight years of mediocre play. This is despite injuries to tight end Eric Ebron and nearly the entire crop of running backs, allowing opposing defenses to largely know the pass is coming.

While part of the credit does belong to Cooter, it's not as simple as saying Cooter turned Stafford around. Even with Cooter at the helm last year, Stafford's efficiency marks didn't come close to what he has done in 2016, and Stafford deserves individual praise for his turnaround.

The Lions have a difficult path ahead with each of their next four opponents ranking in the top 10 of numberFire's schedule-adjusted pass defense rankings. But with a retooled Stafford leading the way, they may be better equipped than they have been in the past to handle such a tricky road.