It's rare to witness an all-time great athlete in his prime. Yet with the New England Patriots, you know you're watching two of the best to ever play their positions. One is, of course, Tom Brady. The other is tight end Rob Gronkowski.

Gronk hasn't even played in the NFL for a full decade, and he has already placed himself in the history books. He's currently ranked 3rd all-time in receiving touchdowns by a tight end with 77. That puts him 4th among all active receivers. Gronkowski isn't just the lunkhead who loves to party. He's an historically good player.

An all-time great who isn't even 30 years old yet, how much is Gronkowski worth?

Rob Gronkowski's Net Worth

According to Celebrity Net Worth, Rob Gronkowski's value is surprisingly low (for an NFL great anyway), especially considering what he has said about his own finances. Gronk's estimated net worth is $15 million.

What makes that such a surprising number is that, if Gronkowski is to be believed, he doesn't spend a cent of the money he makes on football. According to his 2015 memoir It's Good to Be Gronk, he hasn't touched his NFL contract money nor his signing bonus. Instead, he claims he only uses the money he makes from marketing and endorsements.

Considering the money he's made, now playing in his 9th season, if he's telling the truth he must have way more than $15 million in his bank account.

Rob Gronkowski's Contract & Salary

Contract info from Spotrac suggests that Gronk is set to make nearly $10 million combined this year in cash earnings through an $8 million salary, a $1.5 million roster bonus and a $250,000 workout bonus.

What's impressive about Gronk is that he's arguably already destined for the Pro Football Hall of Fame, and is only in his first contract extension. Signed back in 2012, the extension will come to an end after the 2019 season.

Soon after getting drafted in the second round of the 2010 NFL Draft, Gronk signed his rookie deal, worth $4.4 million over 4 years including a $1.76 million signing bonus.

It didn't take long for Gronkowski to become a star -- not just as the best tight end, but one of the best receivers in the NFL. Just two years into his rookie contract, the Patriots decided to make keeping him around long-term a priority. In June of 2012, the team announced they would be signing him to a major contract extension for 6 years, $54 million. That contract included a 2015 option bonus of $10 million if the Patriots were to pick up the final 4 years. Unsurprisingly, they did.

The 2019 season will be Gronkowski's final year on that extension. He'll have a $9 million salary. With bonuses that will bump his cash earnings that year into 8 figures, $10 million.

Rob Gronkowski's Career

Gronk was an extremely well-regarded prospect coming out of the University of Arizona after just two seasons. So much so, in fact, that Bill Belichick and the Patriots traded their second and sixth-round draft picks to the Oakland Raiders, trading up to draft him in the second round, 42nd overall.

Though Rob Gronkowski missed his junior year of college with a back injury before declaring for the draft, he adapted to the NFL remarkably quickly. Appearing in all 16 games of the 2010 season, Gronk caught 42 passes - 10 of which were touchdowns.

If 2010 was the season Gronkowski showed his potential, 2011 was when he became capable of fulfilling it. He started all 16 games and caught 90 passes for 1,327 yards, leading the league with 17 touchdowns as he and Brady's high-powered offense reached Super Bowl XLVI. They would go on to lose to the New York Giants.

He remained a productive player in 2012 and 2013, at least when he was on the field. In what would become a recurring theme for Gronkowski, injuries plagued him and shortened his seasons. He surpassed 10 touchdowns for the 3rd consecutive year in 2012 but an arm injury limited him to 11 games. That arm would require several surgeries, which along with back surgery delayed his 2013 season. He finally played in October, but in only 7 games as a hit to the knee in December tore his ACL and MCL.

Amazingly, he came back from this pretty disastrous series of injuries to play in 15 games in 2014, starting 10. With 1,124 receiving yards and 12 touchdowns, made the AP first All Pro team for the second time, and he made his second Super Bowl as the Pats faced the Seahawks. Gronk caught a touchdown in a dramatic victory for the team, but was also fined over $8,000 for his role in an altercation at the tail-end of the game.

The following year, 2015 saw him sustain that success as he made another All-Pro team and scored 11 touchdowns, his 5th season of 10+ touchdowns in just 6 years.

Then 2016 was another season derailed by injuries. He played in just 8 games, with a herniated disk requiring surgery and ending his season in late November. This relegated Rob Gronkowski to the sidelines during Super Bowl LI, when the Patriots staged an improbable comeback to defeat the Atlanta Falcons in overtime.

Last year, 2017 saw everything one could expect to see in an average Gronk season: great play on the field as well as injuries. He started 14 games and only missed one due to an injury (the other missed game was due to a suspension.) Injuries also put him in danger in the playoffs, as a concussion in the AFC Championship Game against the Jaguars put him in jeopardy of missing another Super Bowl. After getting cleared to play, though, he torched the Philadelphia Eagles defense, scoring 2 touchdowns. Still, the Eagles were victorious.

Rob Gronkowski's Endorsements

Spotrac estimates that after the end of this season, Gronkowski will have over $53 million in cash earnings from the NFL. And as mentioned, that money goes untouched because he makes enough to live off his endorsement deals to.

Gronk is a popular public figure, known as an affable bro who loves to party, so it's no surprise that he became a spokesman for well-known brands like Monster Beverage's (MNST - Get Report) Monster Energy and Dunkin' Brands'  (DNKN - Get Report)  Dunkin' Donuts. He has also been a brand ambassador for beef jerky brand Oberto, and a sponsor for Bodyarmor SuperDrink. Gronk has also graced the cover of Madden NFL 17 for video game developer Electronic Arts' (EA - Get Report) EA Sports.

Rob Gronkowski's House

Gronkowski has a home right in Foxborough, MA, the same city where the Patriots play their home games.

While he was in Minneapolis for Super Bowl LII when the Patriots faced the Eagles, Gronkowski's Massachusetts home was broken into. Among the items stolen were guns, rare coins and watches. Over the next several months Massachusetts police would go on to arrest the three suspects for the break-in.