Since then, the Colts have been to hell and back.
Three weeks into the ensuing campaign, frequently pounded Indianapolis franchise quarterback Andrew Luck suffered a seemingly minor shoulder injury. But injuries would cost Luck the majority of that season, the balky shoulder would linger for the next two years and—after a bungled rehab strategy that backfired on player and team—Luck would eventually have to undergo surgery that sidelined him for the entire 2017 season.
It didn't help that the Indy offensive line remained a dilapidated liability, while Luck had limited weapons on offense and inadequate support from his defense as then-general manager Ryan Grigson missed on several high draft picks (including first-rounders Bjoern Werner and Phillip Dorsett in 2013 and 2015, respectively).
The roster began to decay, and the atmosphere appeared to be toxic under Jim Irsay's ownership.
When the Colts won just four games without Luck and with the league's 30th-ranked defense in 2017, it became hard to believe they were Super Bowl contenders and quite possibly New England's top intra-conference adversary just three years prior.
That sad season concluded just 16 months ago, but with Luck back, a new regime in place and two fruitful offseasons under that front office's belt, the Colts might already have moved back into the prime challenger spot in the American Football Conference.
Here's the how and the why.
Luck could be better than ever
After practically two calendar years' worth of rehab on his throwing shoulder, Luck's immediate impact was limited as the Colts smartly took a slow, cautious approach to his return to game action. The 29-year-old took practically no shots downfield early as the Colts started 1-5.
At the five-week mark, he ranked 32nd among 35 qualified passers with a yards-per-attempt average of 6.1.
But everything began to change when Luck and Co. blew out the Buffalo Bills in Week 7. A well-supported, comfortable Luck made it look easy while throwing four touchdown passes to zero interceptions that day. His broad numbers weren't big, but they didn't need to be, and he seemed to come away from that 37-5 victory with more confidence than ever in his arm as well as his supporting cast.
From that point forward Luck completed 69.5 percent of his passes while posting an 8.0 yards-per-attempt average and a 106.8 passer rating. All three of those statistics ranked in the top seven among 32 qualifiers over the course of that 11-week stretch to conclude the regular season.
Ultimately, Luck finished the year with the highest Pro Football Focus grade of his career. Per the same source, 59.9 percent of his 4,593 passing yards came through the air, which was the thirst-best rate among qualified passers. He also ranked 10th among the same crowd in terms of what PFF calls big-time throw percentage.
There's no reason to think he can't take his game to yet another level in his age-30 season.
Frank Reich is a special coach
Not only did Reich rally his team to the Divisional Round of the playoffs after a 1-5 start, but his forward-thinking, unpredictable, aggressive offensive approach was undoubtedly a breath of fresh air in Indianapolis.
The offensive mastermind devised some magnificent game plans that managed to keep defenses guessing while also taking as much pressure as possible off of Luck. In fact, the beauty of Reich's system is that it doesn't rely on one quarterback, one receiver or one running back.
The Indy offense beat the opposition in almost every way imaginable. Sometimes they won track meets, other times they won in the trenches, sometimes the no-huddle offense was the key, other times play-action was the special sauce.
It was almost impossible to prepare for the Colts offense, or to diagnose it on the fly.
What's scary is Reich and offensive coordinator Nick Sirianni might have only scratched the surface in 2018.
"Every little aspect of it gets evaluated, right? Run game, pass game. How do we improve it? What little tweaks do we have?" Reich said at his end-of-season press conference, per Andrew Walker of the team's official website. "Then Nick (Sirianni) and I will give guys projects. Hey, you go—this team was really good at play-action pass, this team was good at RPOs, go study them. Write a report on this. Make a film. What connects to our offense? What doesn’t? What players did we get in? How do we accentuate what they do well? It’s ever-evolving and it’s fun and exciting."
Chris Ballard is an equally special general manager
In just two years on the job, Ballard has established himself as one of the shrewdest general managers in the NFL. The 2018 Pro Football Writers Association Executive of the Year drafted immediate All-Pros in both Round 1 (guard Quenton Nelson) and Round 2 (linebacker Darius Leonard, who was the Defensive Rookie of the Year) last April, and on Day 2 he also landed rookie starter Braden Smith, who was an asset from the get-go at right tackle.
His first free-agent signing as GM, edge-defender Jabaal Sheard, has been the team's best pass-rusher the last two seasons. Ballard got tremendous open-market value last year for both tight end Eric Ebron and defensive lineman Denico Autry, both of whom played significant roles in 2018. And he's already been widely praised for his work in both free agency and the draft this offseason.
The result? The Colts are deeper than they ever were during Luck's first NFL life.
The offensive line is now one of the best in football
In Luck's first five seasons, his offensive lines earned pass-blocking grades from Pro Football Focus that ranked 31st, 22nd, 16th, 11th and 28th in the NFL. Per PFF's Mark Chichester, the Colts deployed 92 different line combinations with 22 different offensive linemen during that period.
"From 2012 to 2016, he was hit as he threw a whopping 50 times, which was—and still is—a record-high for a quarterback over his first five years in the league," wrote Chichester. "Over that same span, he was either sacked or hit in the pocket a staggering 528 times, which was 34 more times than the next closest quarterback. In the PFF era, only four quarterbacks have been sacked or hit more than 118 times in a single season, but Andrew Luck suffered this fate for three consecutive years."
For much of that stretch, 2011 first-round pick Anthony Castonzo was still developing as a left tackle. And even when it all started to click for Castonzo, a lack of continuity and complementary talent sunk the Indianapolis line.
But Nelson and Smith changed that in 2018, while 2016 first-round pick Ryan Kelly was a strong pass-blocking center when healthy and 2017 Ballard waiver claim Mark Glowinski became a steady presence at right guard.
Incredibly, Luck was sacked on an NFL-low 2.7 percent of his dropbacks in 2018. And there's no reason why his pass protection shouldn't be even better in 2019.
Luck has a loaded arsenal
Between 2013 and 2016, wide receiver T.Y. Hilton was the only non-quarterback at an offensive skill position to make the Pro Bowl from the Colts roster (tight end Jack Doyle was an alternate in 2016). But both Hilton and Ebron were Pro Bowlers in 2018.
The former was one of just three qualified NFL receivers to average more than 16.0 yards per reception while catching at least 63.0 percent of the passes thrown his way, while the latter became just the sixth tight end in league history to score more than a dozen touchdowns in one season.
Meanwhile, a running game that has ranked in the bottom 13 in each of Luck's first six NFL seasons showed plenty signs of life as the 2018 campaign wore on. Sophomore fourth-round pick Marlon Mack was the only player in the AFC to rush for 115-plus yards on five separation occasions (including the playoffs), and three of those performances came in his final five games.
Still, the Colts lacked proven depth beyond Hilton, Ebron and Mack—but that also changed this offseason.
Ballard signed 2015 second-round Carolina Panthers draft pick Devin Funchess, who scored 21 touchdowns in his first four years with Carolina and has yet to turn 25. And then he used a second-round pick on pro-ready former Ohio State receiver Parris Campbell, who should immediately become a Swiss Army knife out of the slot.
If those players can deliver, it might not even matter that they have promising alternatives in Doyle at tight end, Nyheim Hines, Jordan Wilkins and Spencer Ware at running back and Deon Cain and Chester Rogers at wideout.
The defense is...good?
It's hard to fathom, just because that D ranked in the bottom 13 in five of former head coach Chuck Pagano's six seasons running the show, while only three other defenses surrendered more points between 2015 and 2017.
But defensive coordinator Matt Eberflus came over from Dallas and immediately got the most out of Leonard, Sheard, Autry, veteran defensive tackle Margus Hunt and defensive backs Pierre Desir, Kenny Moore and Malik Hooker.
During the final 11 weeks of the regular season, the Colts gave up a league-low 16.4 points per game, and they did so without relying heavily on takeaways (a metric which has a lot of variance from year to year).
Now add four-time Pro Bowl pass-rusher Justin Houston and highly-touted rookie corner Rock Ya-Sin, both of whom were acquired by Ballard this offseason.
The Colts were one of just four NFL teams to rank in the top 10 in terms of both points scored and allowed in 2018, and both units are good enough for that to become a double top-five in 2019.
A wildly fast rebuild is complete
Of course, it wasn't a rebuild from the ground up. It helped that the Colts had Luck in place, and that Grigson at least left this regime with Luck, Hilton, Castonzo and Kelly. They also had to hit on Ballard and Reich, and the latter wouldn't have happened had Josh McDaniels not spurned Ballard and Irsay in the eleventh hour last offseason.
Still, the Colts at least reloaded, and now it feels as though the stars are aligning more precisely.
This team has been built a lot stronger and with fewer vulnerabilities than the one that was crushed by the Pats in both the 2013 and 2014 playoffs.
This new-look Colts squad did play the Pats last year for the first time since Luck was initially dealing with his bad shoulder back in October 2015. They started slowly on the road and lost by two touchdowns, but Luck still wasn't fully re-acclimated, the offense was still getting used to Reich and the revamped defense hadn't hit its stride.
They won't have a chance to send a fresh message to the Patriots in the 2019 regular season, but they will get to face fellow prime New England challengers in the Kansas City Chiefs, Los Angeles Chargers and Pittsburgh Steelers.
Post-draft Super Bowl odds from the Westgate Las Vegas Superbook posted by the Action Network have Indy listed behind only the Pats and Chiefs in the AFC, but Kansas City has experienced a tumultuous offseason and it's gotta be only a matter of time before age, and/or the law of averages, catches up to Tom Brady and the Patriots.
Luck hasn't defeated Brady in six career meetings. Could that change if the two collide for a seventh time in January 2020?
There might not be anyone else in the AFC with a better shot at slaying Goliath.
Brad Gagnon has covered the NFL for Bleacher Report since 2012.