A second-round draft pick in 2010, Gronkowski had two years remaining on his rookie deal, and the base salaries for those years are largely unchanged - he’ll make $540,000 for the upcoming season and $630,000 for 2013, both fully guaranteed - but the new money for the short term comes in the form of an $8 million signing bonus, which he’ll receive immediately.

His base salaries in 2014 and ’15 jump to $3.75 million and $4.75 million, respectively.

And it’s possible the deal could end there, when Gronkowski is still shy of his 27th birthday. It could continue for another four years if the Patriots pick up a $10 million option bonus in 2016. If they do, Gronkowski would be slated to earn a total of $26.97 million in salary from 2016-19.

One detail NFL Network revealed: If New England opts not to pick up the option bonus in ’16, it cannot place the franchise tag on Gronkowski, which would effectively make him a free agent in what would be the prime of his career.

There was no announcement from the Patriots, but agent Drew Rosenhaus tweeted, “Congrats to Gronk & his family on his contract extension with the Patriots. My thanks to Mr. [Robert] Kraft & Coach [Bill] Belichick for making this possible.’’

There is no denying that Gronkowski was outperforming the four-year, $3.6 million contract he signed coming out of the University of Arizona in 2010, when he slid in the draft because of health concerns. Gronkowski missed his junior season because of back surgery, but still elected to enter the draft.

He has had no known issues with his back in two seasons with the Patriots, and has yet to miss a game. Last year, he established himself as the NFL’s best tight end, setting records for the position of 1,327 receiving yards and 18 touchdowns (17 receiving, one rushing) on 90 catches.

Gronkowski suffered a severely sprained left ankle in the AFC Championship game, but still was on the field two weeks later in Super Bowl XLVI, though he was clearly hobbled. Not long after the season, he underwent surgery to repair torn ligaments, and continues to rehab.

Over the last decade-plus, the Patriots have been loath to re-up young players before their contracts expired, leading to difficult (at best) to ugly (at worst) contract battles with the likes of Asante Samuel, Vince Wilfork, and Logan Mankins.

Last December, however, the team extended linebacker Jerod Mayo with 18 months remaining on his rookie deal, through 2017, and now has extended Gronkowski two years before his contract was set to expire.

With Gronkowski locked up, it will be interesting to see if the Patriots turn their attention to other core players who are nearing the end of their rookie pacts: deals for Patrick Chung and Sebastian Vollmer end after the 2012 season, and Aaron Hernandez after the 2013 season.

Greg A. Bedard of the Globe staff contributed to this report. Shalise Manza Young can be reached at syoung@globe.com. Follow her on Twitter @shalisemyoung.