Northwestern cornerback Matthew Harris came into 2016 as one of the top defensive players in the conference. But the 2015 All-B1G honoree only played in two games this season.

Now, he’s calling it a career because of concussions.

“This is an incredibly difficult decision to reach, but it is the right one for me and for my future,” Harris said in a statement. “I’m so thankful for Coach Fitzgerald, Coach Brown and the rest of the staff that brought me to Northwestern and have mentored me over the last several years. My teammates are like brothers, and while not being on the field with them has been frustrating and challenging, I’m so proud of the group and what we’ve helped build together.

“I owe thanks to our athletic training and sports medicine staffs, whose care throughout my Wildcats career has been outstanding. Finally and most importantly, I can never appropriately express the love and gratitude I have for my family, which has supported me on every step of this journey and will continue to for years to come.”

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Harris hadn’t played since suffering a concussion in Week 2 against Illinois State.

The senior finished his career with 161 tackles, 4.5 tackles for loss, six interceptions and three forced fumbles. He led one of the top secondaries in the country last year and was named a team captain entering 2016.

In addition to his leadership on the field, Harris led off the field. He’s still the co-President of Northwestern’s Student-Athlete Advisory Committee and is is one of two Wildcats representatives to the Big Ten Student-Athlete Advisory Committee.

Northwestern will take on No. 6 Ohio State on Saturday in Columbus.