Adelaide have opted not to match St Kilda's free agency offer for Brad Crouch, meaning he is now officially a Saint.

The Saints submitted the paperwork on Sunday to secure Crouch on a four-year deal reportedly worth around $700,000 a season with a trigger for a fifth year, with the Crows getting three days to match the offer.

Adelaide took all the way up until the 5pm Wednesday AEST deadline, ultimately deciding to let the midfielder walk as a restricted free agent.

The Crows will receive a second round compensation pick as a result, currently the No. 23 selection.

Adelaide released a statement thanking Crouch for his contributions to the club.

“We wish Brad and his partner Britney all the best for the future as they head to Victoria with many strong friendships from their time here,” Crows General Manager List Management and Strategy Justin Reid told the club website.

Reid also explained the club's decision not to offer the 26-year old a long-term contract.

“We are committed to making decisions in the best interests of the entire playing group and Club, and did not see a lengthy deal as responsible list management in this instance,” Reid said.

“The AFL’s free agency rules determine what compensation is received in return for a departing player.

“Ultimately, the risk versus reward of matching St Kilda’s offer and trying to force a trade, for say their first Round selection at pick 17, which might not eventuate, didn’t stack up.

“We acknowledge there will be plenty of debate, and in some cases frustration, among our Members and fans about the merit of accepting the compensation but we exhausted all available options.”

Crouch played 95 AFL games for the Crows over eight seasons after making his debut in 2013.