Andrew Luck signs extension with Colts

— -- Indianapolis Colts owner Jim Irsay stuck to his word and locked up franchise quarterback  Andrew Luck long term before the start of the season. 

The team announced Wednesday that Luck has signed an extension through the 2021 season. Financial terms weren't immediately announced. 

The No. 1 overall pick in 2012 out of Stanford, Luck took the NFL by storm the moment he stepped onto the field for the Colts. He made the franchise's transition from Peyton Manning a smooth one by leading it to the playoffs in each of his first three seasons, including the AFC Championship Game in 2014 and back-to-back AFC South titles.

He has the fourth-most passing yards (14,838) by any quarterback in his first four seasons in NFL history. He also is the fourth QB with at least 100 touchdown passes through four years, including an NFL-leading 40 in 2014. 

But Luck isn't immune to struggles, either.

The 26-year-old is coming off the worst season of his four-year NFL career, completing just 55.3 percent of his pass attempts and committing 13 turnovers in 2015. He also showed he's not invincible when it comes to taking hits. He missed two games early in the year due to a rib injury and then he missed the final seven games when he suffered a lacerated kidney early in the fourth quarter against the Denver Broncos in Week 9. He also dealt with shoulder and abdominal injuries.

Irsay said earlier this month that he would be "surprised" if the Colts did not agree to a long-term contract extension with Luck. 

Luck, in turn, said he wasn't overly concerned about getting a deal done. 

"As far as the importance of getting it done or not, if it happens [before training camp], great," Luck said earlier this month. "If it doesn't happen [before training camp], great too. I know I'm a Colt and I'm going to do the best job I can for this team, no matter what the situation is. So it doesn't weigh on me."

The Colts report to training camp July 26 at Anderson (Indiana) University.

Information from ESPN's Mike Wells was used in this report.