Detroit Lions 2015 Year in Review: Calvin Johnson's Last Ride

Calvin Johnson decided to retire at the end of the 2015 season, which wasn't a particularly good one for Detroit. Where do they go from here?

Superstar wide receiver Calvin Johnson won't be chasing any Super Bowl rings.

After nine mostly prolific NFL seasons, Johnson has decided to retire. Since picking the man named Megatron second overall in the 2007 NFL Draft, the Detroit Lions have gone just 54-90 with no division titles and only two wild card losses in their only playoff appearances.

Say whatever you want about how he didn't lead his team to victory: Calvin Johnson was better even in his final few season than you probably realize.

No, this isn't all about Johnson, but the departure of the one constant in an otherwise shaky franchise over the past decade deserves attention.

Plus, there wasn't too much else to talk about from their 7-9 campaign in 2015.

What Went Right?

Detroit was an average offense in 2015, ranking 16th in our schedule-adjusted Net Expected Points (NEP) metric, which you can read more about in our glossary.

They ranked 14th in opponent-adjusted passing efficiency and 17th in rushing efficiency. For the sake of being optimistic, we'll have to count those as positives.

We may as well just start with the quarterback: Matthew Stafford. Stafford wound up 16th in Passing NEP (65.44) among 37 passers with at least 200 drop backs in 2015. On a per-play basis, his 0.10 score also ranked 16th. Perhaps the silver lining here is that his Passing Success Rate -- the percentage of drop backs that led to NEP gains -- of 51.10% ranked seventh.

That was his best output since his career year in 2011 (51.65%) when his Passing NEP was 112.26. For more perspective, he's topped 46.66% just one other time (2012). This means that he wasn't as reliant on big plays to boost his NEP. He was more methodical than almost ever before.

Helping him get there, of course, was Calvin Johnson, whose 105.07 Reception NEP ranked 10th among all receivers. Golden Tate's 64.60 ranked just 39th.

Among 32 receivers with at least 100 targets last season, Johnson's Reception NEP per target (0.71) ranked 16th. Tate's 0.50 ranked 31st. Per reception, Johnson's 1.19 ranked 15th, and Tate's 0.72 ranked 32nd (i.e. last).

And among the 28 tight ends with at least 50 targets, Eric Ebron ranked 11th in Reception NEP per target (0.64) but just 14th in Reception NEP (44.49). Any way you want to look at his metrics -- per catch, per target, overall -- he was average among guys with similar volume.

Similar to the passing offense, we'll have to consider the 17th-ranked rushing offense a positive, too, though it certainly had some holes.

Joique Bell -- not Ameer Abdullah -- led the backfield in Rushing NEP. Among the 55 backs with at least 75 carries, Bell's -1.58 mark over 90 totes ranked 16th. Abdullah's -4.85 ranked 28th over 143 carries.

Surprisingly, though, it was the explosive Abdullah who had the better Success Rate (42.66%, 15th in the group) and not the big-bodied Bell (36.67, 37th).

The real star of the backfield, however, was Theo Roddick, whose 49.81 Reception NEP was second among all running backs.

What Went Wrong?

With basically an average NFL offense last year, there had to be a reason why our algorithms viewed the Lions as about 3.5 points per game below average.

That was primarily the defense, which ranked 26th in Adjusted Defensive NEP per play. They were 22nd in rushing defense and 25th in passing defense, per our metrics.

Detroit also ranked 23rd in first downs per play against and faced the 10th-most red zone plays on defense, allowing first downs at the 5th-worst rate with their backs to the goal line.

On the other side of the ball, the offensive line also capped the upside of the team, allowing the 10th-most sacks in the NFL.

Stafford lost 64.16 points on sacks this season, seventh-most in the NFL. He was just 19th in Sack NEP lost per drop back, but among the 28 passers with at least 300 drop backs, he lost the 10th-most points on a per-sack basis.

It's no secret that Stafford is a volume passer, but that doesn't excuse the costly sacks and will continue to be something the Lions need to hone in on if they want to make the most of their offensive pieces -- now without Calvin Johnson.

What's Next?

That depends on what new general manager Bob Quinn wants to do.

The good news is that he's optimistic, stating that Detroit is an attractive place for NFL free agents and that the Lions are "better all around" after the first wave of free agency.

The most noteworthy moves were releasing Joique Bell, signing wide receiver Marvin Jones and re-signing Haloti Ngata.

The team also lost Rashean Mathis to retirement as well as Johnson. Ultimately, Quinn is seeking to give something Detroit they haven't had in some time: reliable depth.

Quinn's success as general manager as well as Stafford's play will ultimately determine whether this team can reach the postseason next season.