The 2018 season came to a bit of a bitter end for the Tennessee Titans on Sunday night. In losing to one of their biggest rivals, the Colts, they missed out on a playoff berth and gave Andrew Luck his eleventh straight victory over the team.

With 2018 now at an end, it is an appropriate time to look back on the season as a whole. Here are the five biggest observations one can make of the 2018 Titans season.

1. All the Craziness

If first-year head coach Mike Vrabel thought that life in the NFL would be predictable and consistent from day to day, he was quickly proven wrong.

In week one, the Titans participated in the NFL's longest-ever game. Their seemingly never-ending showdown against the Dolphins featured three rain delays and lasted 7 hours and 8 minutes.

"We didn’t cover that one in the offseason manual," Vrabel said in his end-of-season press conference.

Though the Titans' mystical game in South Beach may have been the team's weirdest experience of the season, it was far from being their only crazy one.

At the end of Week 2, safety Kevin Byard was tied for the team lead in touchdown passes. Safety Dane Cruikshank led the team in receiving.

Following the Titans' Week 3 victory in Jacksonville, one of their starters on offense literally quit the team. Veteran receiver Rishard Matthews, who had missed all of Training Camp with an injury, requested a release or trade due to issues with his playing time. He had just signed a contract extension with the team.

Week 4 gave Titans fans arguably the most exciting game to ever be played in Nissan Stadium. The Titans converted three fourth downs in overtime en route to a thrilling victory over the reigning Super Bowl champion Philadelphia Eagles.

Against the Colts in Week 11, the Titans lost a member of their coaching staff early in the game. Defensive coordinator Dean Pees was taken to a nearby hospital in Indianapolis due to symptoms resembling a stroke. Tennessee's defense imploded after that, ultimately allowing the Colts to score 38 points in a one-sided loss.

Through the end of November, running back Derrick Henry was among the NFL's least productive ballcarriers. In the month of December, he turned things around and became one of the most productive. More on that to come.

Further searching and nitpicking would probably reveal more crazy things that the Titans were forced to endure in 2018, but this list should suffice.

The Titans had to put up with a lot this season, and most of the things they had to put up with can't exactly be mimicked with practice reps.

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2. "Weenie Hut General"

"Next man up" is a very common principle that football coaches preach to the point of it being cliche, and that certainly is not a bad thing.

Depth is important, as injuries are bound to happen in a sport as violent as NFL football often is. There are some situations, however, when no amount of depth can save the fate of a team.

The Titans suffered a ridiculous number of injuries over the course of the 2018 campaign, and most of them weren't to marginal or role players.

From the start of Training Camp through Week 17, the Titans lost the following players to season-ending ailments: CB Tye Smith, S Johnathan Cyprien, TE Delanie Walker, T Jack Conklin, CB Logan Ryan, DL Jurrell Casey, LB Brian Orakpo and TE Jonnu Smith.

That list doesn't include players who missed significant chunks of time throughout Training Camp and the regular season. LB Rashaan Evans, S Kenny Vaccaro, S/ST Dane Cruikshank, RB/ST David Fluellen and LB Derrick Morgan all fall within that category.

Additionally, QB Marcus Mariota missed two games, including the Titans' season finale against the Colts.

"Yeah, it’s awesome," said tackle Taylor Lewan, asked about the prospect of getting all of those injured players back next season. "That’s the thing with playing this sport is you’re going to get injured. Everyone’s injured. I’m injured, Dennis [Kelly] is injured, everyone’s hurt. That’s what it is. Will guys get hurt next year? No question, that’s how it works."

Amazingly, the Titans were able to put together a nine-win season amidst all of those injuries. That speaks both to the team's depth and its character. More on the latter below.

3. Resiliency

In the early days of Training Camp, Mike Vrabel made the comment that moments of adversity would "reveal the character" of his football team. The Titans endured many of those moments in 2018.

All of the aforementioned injuries and times of craziness snowballed to give the Titans a storm that the "curveball" metaphor would not suffice to describe. It was more like a Mariano Rivera cutter, which many considered to be an un-hittable pitch.

Yet, the Titans managed to hit it. After all that they went through, the Titans were a touchdown drive away from tying-up a Week 17 win-and-in game. They may have lost, but it was pretty impressive that they were even in that spot to begin with.

If adversity reveals the character of a team, as Vrabel said it does, then the Titans were shown in 2018 to be a scrappy, resilient bunch. They stepped up to the plate on every challenge they were faced with, often emerging victorious.

"When all that adversity’s going on," said linebacker Will Compton, "you find out what teams rise to the occasion and it was awesome to be part of it on this team. There was a moment there before these last four or five weeks where you’re thinking, ‘man, we’re probably not in it, we’re not going to make it.’ Then you rattle off four in a row and lose a tough one last night. It just speaks volumes to how resilient this team is."

Fans of the Titans should be encouraged by what the team was able to do with all of the difficult, uncontrollable circumstances they faced in 2018. With more normalcy next season, this team could do some very good things.

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4. King Henry Earns His Crown

In December alone, Derrick Henry ran for 625 yards and 8 touchdowns.

His turnaround, which began with his monumental effort against the Jaguars in Week 14, was nothing short of impressive.

He didn't really prove his doubters wrong, as the third-year back from Alabama was indeed really bad for the first three months of the season. He lacked burst, vision, and he struggled to do anything productive with the ball in his hands.

But for whatever reason, when the calendar turned to December, Henry became one of the NFL's best. He ran with power and pure speed, refusing to be brought down in most situations. He was a big reason why the Titans were able to go on their four-game win streak at the end of the season.

Henry was expectedly named the AFC's Offensive Player of the Month for December.

The big question for Henry, at this point, is what the future holds for him. Will he keep up the style of running he used in December, or will he again disappoint and revert to his old self?

"I'll use the momentum in the offseason to get better," Henry said. "Continue to improve at those things I need to get better at and get ready for April when we come back in here…Every aspect of my game, I can get better at and improve on a lot. That's the focal point, improving on those things."

A motivated and further-improved Henry would certainly be a welcomed sight for the Titans in 2019.

MORE: Mike Vrabel, Marcus Mariota Speechless at Derrick Henry's Performance

5. Mariota Still a Question Mark

Many analysts considered 2018 to be a crucial season for quarterback Marcus Mariota, that it would be the season where the Titans finally learned once and for all whether he is their franchise quarterback.

Alas, that did not come to fruition. 2018 is over, and there are still far more questions than answers surrounding Mariota.

The Oregon-product is set to play the 2019 season on his fifth-year option, which is totaled at nearly $21 million. Beyond that, things get murky. He is currently set to be an unrestricted free agent in 2020.

The Titans could certainly give Mariota a contract extension at some point over the next few months, but that seems like a risky decision considering the many uncertainties surrounding his on-field performance.

Another option the Titans have is allowing Mariota to play out his rookie contract and then give him the franchise tag at the end of 2019 if they decide they want to keep him around. That could serve as a placeholder for a more conventional, long-term contract.

With another year under their belts in offensive coordinator Matt LaFleur's system, Mariota and the rest of the offense should see a substantial amount of improvement next season. The question lies in just how much money that improvement will be worth.

MORE: Behind the Scenes of Marcus Mariota's Unique Leadership Style