Kevin Garnett officially announced his retirement from the NBA on Friday, and over the next few days you'll hear a lot of talk about his numbers and other certain Hall-of-Fame credentials. And rightfully so. Garnett is one of the best players of his generation. One of the best players of all-time, really.

But unlike a lot of other players, even great ones, when the dust settles and we're years down the road, Garnett's legacy will ultimately be defined by a lot more than his menacing scowl and absurd statistics on basketball reference.

Kevin Garnett started NBA revolutions.

With more coverage surely to come on Garnett and all he has meant to the game of basketball, right now here are what will, in my opinion, prove to be KG's three most lasting impacts on the NBA.

High School to Pros Movement

Garnett wasn't the first player to jump from high school to the NBA. Moses Malone, Darryl Dawkins and Bill Willoughby all did it within two years of Garnett's birth in 1976. But Garnett reopened that door in 1995, and along with Kobe Bryant, who made the jump straight from high school a year after Garnett, he will absolutely go down as one of the poster prep-to-pro players -- not just because he made that jump and made that a very real possibility for the era of players we see now doing it all the time, but because he become a first-ball Hall of Famer in doing so.

Back when Garnett was having his big individual workout for teams all over the NBA, the Timberwolves' Flip Saunders and Kevin McHale went into the workout hoping to trick teams into thinking they'd select KG with the No. 5 pick in the draft, hoping that in turn those teams ahead of them would bite on the interest, reach for KG, and leave Rasheed Wallace or Jerry Stackhouse to fall to Minnesota's spot.

In other words, they didn't want Garnett.

Shortly after KG wowed everybody in the workout, however, Saunders and McHale changed their tune pretty quickly and started praying Garnett woudl fall to him. He did, and shortly thereafter the Wolves made eight straight postseason appearances -- the only eight postseason in franchise history, incidentally.

Garnett made an immediate impact in the league, his almost psychotic competitiveness fueling an unreal level of focus and determination. He slapped the floor and barked maniacally at opponents when they had the ball. His sinewy frame cut off large sections of the court and made opponents feel like they had nowhere to go. He was basically a 7-footer with guard skills, challenging everything we thought we knew at the time about players that size. Garnett, in many ways, began the evolution of the forward and center positions to a more mobile, athletic player with real perimeter talent.

"Man, when you're a rookie you need everything," former Wolves coach and Garnett teammate Sam Mitchell told me last season. "Have you ever seen a rookie come into this league and have a complete game? KG was no different. Only difference was is he had a high basketball IQ so he picked up things really simple and easy. The thing we found amazing about him is if you show something one time, he generally got it. You didn't have to go over and over and over."

It was that ability to adapt quickly to what the Wolves needed him to do, even as a teenager, that helped put to rest the concern around the NBA that high school players weren't ready for so much responsibility.

From 1995 to 2005, 39 players including Garnett were selected in the NBA draft straight out of high school. Players like Kobe, Tracy McGrady, LeBron James, Amar'e Stoudemire, Dwight Howard, Jermaine O'Neal and Tyson Chandler all followed Garnett's lead by forgoing college and believing they were good enough to play with the best in the world right away. There were some awful failures in the process, but of the players in this decade or so of guys jumping to the NBA, you could create one of the greatest teams of all-time.

It's not that without Garnett players would've never tried this, but he opened up the door and created a flurry of options for young players that eventually had to be closed off with the NBA implementing an age limit of 19 years old or one year removed from your high school graduating class that started in 2006.

Good times in Minnesota. Getty Images

The 1998 NBA Lockout

In 1998, Wolves owner Glen Taylor gave Garnett what was, at that time, the biggest contract in NBA history -- six years, $126 million, even more than the seven-year, $121 million deal Shaq had gotten from the Lakers a year earlier.

It's not that Garnett wasn't worth the money. By the end of his third season, Garnett was averaging 18.5 points, 9.6 rebounds, 4.2 assists, 1.8 blocks, and 1.7 steals just as he was becoming legally allowed to drink alcohol. He was the only player in the NBA putting up 18-9-4 every night that season, was learning how to play world class defense, and he was already a two-time All-Star.

But paying that kind of money to a 21-year-old player was not a precedent the owners wanted to set. Yes, they had curbed rookie salaries, but players like Garnett had the ability to escape these contracts and become free agents after three years. Nowadays a player stays on his rookie deal for four years, and even then he only becomes a restricted free agent. The owners also wanted to implement max salaries.

The NBA had its biggest lockout from July 1, 1998 to January 20, 1999. They avoided losing an entire season and settled on a truncated 50-game schedule in 1999, but from that point forward, it was going to be much harder and a much longer process for young players to end up with the type of money KG earned that early in their career, and even then the owners were going to cap those potential earnings for as long as possible.

The Big Three Era

For 12 years, Garnett stayed loyal to the Timberwolves. He never requested a trade even when they were losing draft picks for an illegal free-agent deal. He rode with the idea that Rasho Nesterovic and Trenton Hassell were playing the most games alongside him. He took the brunt of the criticism whenever they were bounced from the playoffs early on and when they no longer could make the postseason at all. KG wore every single bad thing as much as he celebrated the successes of his team. He didn't always do it with a sparkling personality behind the scenes, but he did it publicly.

Eventually, enough was enough. He was nearly traded to the Phoenix Suns in 2007, but after Shawn Marion's salary demands crippled the potential three-team deal, the Wolves -- still run by McHale -- tried to trade Garnett to the Boston Celtics so he could join up with Paul Pierce and make a run at a title. However, Garnett refused to sign an extension with the Celtics in a way to remain loyal to the Wolves' organization and ruin any chance of a trade.

However, after some contemplation and the Celtics managing to move Jeff Green, Wally Szczerbiak and Delonte West to Seattle in exchange for Ray Allen and Glen Davis, KG was ready to accept a trade, an extension, and a new uniform. The two trades by Danny Ainge formed a Big Three and while it wasn't the first Big Three in NBA history, it was quickly being marketed as if the Celtics trademarked the term like Pat Riley and 3-peat. Championship expectations were being piled on Pierce, Garnett and Allen, all ringless veteran, and they immediately took to Doc Rivers' guidance and sense of team.

When you think Big 3, this, for many people, is where it started. Getty Images

Their first season together, the Celtics defeated the Lakers in six games in the 2008 NBA Finals. KG got his ring, shouted "Anything is possible!" at Michele Tafoya and the heavens above, and dedicated his accomplishment to Minnesota for something they could never quite figure out during his tenure there. It was eye-opening for stars around the league who were saturated with the idea of team loyalty for decades of professional sports narratives.

It was finally more acceptable to see the lay of the NBA, realize your situation was unlikely to yield the championship rings you ultimately get judged for having or not having, and find greener pastures. Seeing the Celtics have instant championship success showed young stars around the league it might be more fruitful to do this type of move now rather than more than a decade in when your window is much smaller for bringing home that title. It wasn't knocking loyalty as much as it was reminding players your legacy will be defined by titles and you better find a way to one if your incumbent franchise isn't able to pull it off.

Two years later, LeBron James, Dwyane Wade and Chris Bosh were teammates in South Beach. Carmelo Anthony found his way to Stoudemire and the Knicks as they tried to build their own Big Three. The Los Angeles Clippers were trying to make Chris Paul accelerate the learning process for Blake Griffin and DeAndre Jordan in a calculated but desperate attempt at having that coveted trio. The Lakers even tried taking it a step further by putting Dwight Howard and Steve Nash with Kobe and Pau Gasol.

Now it's evolved into the super team with Kevin Durant on the Golden State Warriors as everything over time has to get bigger and better on some level. But for this modern era, KG agreeing to that trade started what we have come to know as a true NBA Big 3.

Along wit the lockout and the prep-to-pro movement, KG revolutionized more than just his position or the way we think about big men on the court. He changed the way the league operates. It can be overlooked over the years but when you go back and really pay attention to what happened around his career, it's even more remarkable on every level.