The Pittsburgh Steelers drafted former Florida offensive tackle Marcus Gilbert with the 63rd overall pick in the second round of the 2011 NFL Draft. Gilbert played eight seasons with the Steelers before being traded to the Arizona Cardinals in 2019.An unfortunate injury led to Gilbert opting out of the 2020 NFL season. Marcus Gilbert never played a single snap for the Arizona Cardinals after being traded. He announced his retirement on Monday. This brings the question of why Marcus Gilbert decided to retire?Why did Marcus Gilbert decide to retire on Monday?Former Steelers OT Marcus GilbertIn his ten-year NFL career, Marcus Gilbert has only played 100% of snaps once. That came during the 2015 season with the Pittsburgh Steelers. Gilbert's second best season was the 2013 season where he played 90% of the snaps for Pittsburgh.Marcus Gilbert announces his retirement. Was one of the best right tackles in football with the #Steelers before injuries mounted. https://t.co/6xhTdDUMEE— Jeremy Fowler (@JFowlerESPN) April 26, 2021When Marcus Gilbert was healthy, he was a great offensive lineman and played well for the Pittsburgh Steelers. Gilbert won the starting offensive tackle position during the 2012 NFL season. This came one season after the Pittsburgh Steelers gave him the rookie of the year award for the franchise.After being named the starter in 2012, Marcus Gilbert suffered a season-ending injury after starting five games. During the 2017 season, Marcus Gilbert was suspended by the Pittsburgh Steelers for violating the league's performance enhancing drugs policy. Gilbert was placed on the injured reserve list for both the 2018 and 2019 NFL seasons.The most recent injury that Marcus Gilbert suffered turned out to be the last injury of his NFL career. Gilbert had a torn ACL that ultimately made him hang up his cleats on Monday. Marcus Gilbert had this to say about his journey throughout his NFL career in his retirement speech on Monday:"After ten seasons playing in the National Football League, I have decided to retire. I will forever remain grateful for the memories, experiences, friendships and successes football has provided me. I am thankful for the coaches, doctors, trainers and staff that have helped me along the way."After a decade in the NFL, former #Gators offensive lineman Marcus Gilbert is officially retiring from football.“I will forever remain grateful for the memories, experiences, friendships and successes football has provided me.”STORY: https://t.co/E2hufaoJY5 pic.twitter.com/dn1xECXmLj— Corey Bender (@Corey_Bender) April 26, 2021Marcus Gilbert went on to thank the Pittsburgh Steelers organization and wished the Arizona Cardinals the best for their future. Gilbert also thanked his family for standing by his side throughout his career. His NFL career had its ups and downs, but Marcus Gilbert gave it everything he had throughout his ten years in the NFL.