Jacksonville Jaguars linebacker Paul Posluszny, the second-leading tackler in franchise history, is retiring from the NFL after 11 seasons.

The 33-year-old Posluszny announced his decision in a letter to fans Tuesday, one day before he was scheduled to become an unrestricted free agent.

Posluszny started his career in Buffalo before playing the final seven years in Jacksonville. He led the Jaguars in tackles five times. His 973 stops trail only Daryl Smith (1,089) in Jacksonville's record book.

Posluszny says "with much sadness but without regret, I realize that I am no longer able to adhere to the unwavering standard of excellence that professional football demands.''

He adds that he can "no longer compete at a level that I find acceptable.''

Posluszny, 6-2, 232, appeared in 145 career regular season games, totaling 1,381 tackles (984 solo), 41 passes defensed, 16.0 sacks, 15 INTs, eight forced fumbles and three fumble recoveries. He was a second-round pick (34th overall) of the Bills in 2007, and is one of only two players to record at least 15.0 sacks and 15 INTs, and his 1,381 tackles are the most in the NFL over that span (Karlos Dansby is the other).

The former Penn State linebacker served as team captain for five seasons in Jacksonville and appeared in 100 games after signing with the Jaguars as an unrestricted free agent in 2011.  He made his first career postseason appearance in 2017, during the Jaguars' memorable run to the AFC Championship Game.