For the better part of the last decade, the Indianapolis Colts have dominated the AFC South. Since it was created in 2002, they've won the division title nine times with the Houston Texans winning it three times and the Tennessee Titans twice in that span. The reason for that is fairly obvious: Peyton Manning and Andrew Luck.

The Colts have had the best quarterback in the division since its inception 14 years ago. And while that's not going to change for at least another five-plus years with Luck at the helm, the rest of the division is closing the gap with Indianapolis.

The 8-8 Colts relinquished the AFC South in 2015 after Luck went down with an injury and missed nine games. The Texans took advantage of the opportunity and won the division, albeit with an underwhelming 9-7 record. But Houston is going to be better than it was last season, and so will the rest of the AFC South -- all the way down to the Jacksonville Jaguars.

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How have the other three teams caught up to the Colts? The same way the Colts have dominated for nearly 15 years: with their quarterbacks. The Texans signed Brock Osweiler to a four-year, $72 million deal in free agency, giving them what they hope to be a franchise quarterback going forward. The Titans went a different route to nab their starter Marcus Mariota, taking him second overall in 2015. The Jaguars did the same in 2014, selecting Blake Bortles third overall in 2014.

Of course, none of the three are what you would call stars, but they're all on the rise. Osweiler showed flashes and great potential in place of Manning last season for the Broncos. Mariota, despite dealing with a knee injury, put together a stellar rookie campaign with 19 touchdowns in just 12 games, and 2,818 yards through the air. Bortles, the most experienced starter of the bunch, took a huge step forward in 2015, tossing 35 touchdowns and 4,428 passing yards despite getting sacked 51 times due to poor offensive line play.

You'd be foolish to expect these three quarterbacks to regress in 2016, which means one thing: The Texans, Jaguars and Titans are going to improve next season.

All three made big additions to their rosters in the offseason. The Titans added DeMarco Murray and a boatload of rookies, including offensive tackle Jack Conklin, defensive end Kevin Dodd and Derrick Henry, who will pair with Murray to give Tennessee a bruising backfield. They also added Rishard Matthews, who will be a dynamic receiver for Mariota.

The Texans weren't quiet this offseason, either. In addition to signing Osweiler, they added Lamar Miller in free agency and drafted two immediate starters in wideout Will Fuller and center Nick Martin. And as if Osweiler didn't have enough weapons, the Texans also took Braxton Miller in the third round and speedster Tyler Ervin in the fourth.

For as much as the Texans and Titans added, no AFC South team will have a better young defense than the Jaguars. Jalen Ramsey, Myles Jack and Dante Fowler will all come in and start from Day 1, immediately making the defense better than it was in 2015. Prince Amukamara, Tashaun Gipson and Malik Jackson were all huge free agent additions, all of which will become starters, too.

So, who did the Colts add? Outside of cornerback Patrick Robinson and rookie center Ryan Kelly, the Colts didn't make any impact additions this offseason. Second-round pick T.J. Green is an athletic but raw safety who will certainly take some time to develop. Le'Raven Clark could potentially start at right tackle after being taken in the third round, but he's not a blue-chip talent by any means.

Of the four teams in the division, the Colts had the worst offseason, and it's not even close. Of course, teams aren't made or broken in one draft or free agency, but the Colts have holes all over the field. The secondary is aging and doesn't have many impact players outside of Vontae Davis and 35-year-old Mike Adams. The pass rush only recorded 35 sacks in 2015, which was 22nd in the NFL.

And on offense, 33-year-old Frank Gore failed to rush for more than 1,000 yards and his backup is Robert Turbin, who has 1,127 career rushing yards in four years. And that offensive line? It allowed 37 sacks in 2015 and hasn't done nearly a good enough job protecting Luck.

The Colts are still the team to beat in the division simply based on the fact that they have Luck, who's the best quarterback in the AFC South. But the race is going to be much, much closer than it's been in recent years. For the first time in recent memory, the Colts have a serious challenge in the division, and it's going to be fun to watch.

You could make the case that no division has better young talent at quarterback than the AFC South. And as we all know, it's a quarterback-driven league.