Question: What former LSU Tigers defensive coordinator led the 2015 Youngstown State Penguins football team?

Context articles: Stambaugh Stadium
Youngstown State Penguins football
2017 Youngstown State Penguins football team
2016 Youngstown State Penguins football team
Bo Pelini
2011 Youngstown State Penguins football team
2014 Youngstown State Penguins football team
2015 Youngstown State Penguins football team
2012 Youngstown State Penguins football team
Carl Pelini

Stambaugh Stadium, officially Arnold D. Stambaugh Stadium, is a multi-purpose stadium in Youngstown, Ohio, United States, on the campus of Youngstown State University.
 The stadium was built in 1982, and is primarily used for American football.
 It is the home venue for the Youngstown State Penguins football team, a member of the National Collegiate Athletic Association (NCAA) at the Division I Football Championship Division (FCS) level and the Missouri Valley Football Conference.
The Youngstown State Penguins football team represents Youngstown State University in college football.
 Youngstown State currently plays as a member of the NCAA at the NCAA Division I Football Championship Subdivision (formerly known as Division I-AA) and are a member of the Missouri Valley Football Conference (MVFC).
 The Penguins have played their home games in Stambaugh Stadium, more commonly called "The Ice Castle," since 1982.
The 2017 Youngstown State Penguins football team represent Youngstown State University in the 2017 NCAA Division I FCS football season.
 They are led by third year head coach Bo Pelini and play their home games at Stambaugh Stadium.
 They are a member of the Missouri Valley Football Conference.
The 2016 Youngstown State Penguins football team represented Youngstown State University in the 2016 NCAA Division I FCS football season.
 They were led by second year head coach Bo Pelini and played their home games at Stambaugh Stadium.
 They were a member of the Missouri Valley Football Conference.
 Youngstown State finished the season 12–4 overall with a 6–2 mark in MVFC play to finish in third place.
 They received an at-large bid to the FCS playoffs, where they defeated Samford, Jacksonville State, Wofford, and Eastern Washington to advance to the National Championship Game, where they lost to James Madison.
Mark Anthony "Bo" Pelini (born December 13, 1967) is the American football head coach for the Youngstown State Penguins football team at Youngstown State University.
 He served as head coach of the Nebraska Cornhuskers from December 2007 until November 2014.
 Prior to leading the football program at Nebraska, he was the defensive coordinator for the LSU Tigers, Oklahoma Sooners, and the Nebraska Cornhuskers.
The 2011 Youngstown State Penguins football team represented Youngstown State University in the 2011 NCAA Division I FCS football season.
 The Penguins were led by second year head coach Eric Wolford and played their home games at Stambaugh Stadium.
 They are a member of the Missouri Valley Football Conference.
 They finished the season 6–5, 4–4 in MVFC play to finish in a tie for fourth place.
The 2014 Youngstown State Penguins football team represented Youngstown State University in the 2014 NCAA Division I FCS football season.
 They were led by fifth-year head coach Eric Wolford and played their home games at Stambaugh Stadium.
 They were a member of the Missouri Valley Football Conference.
 They finished the season 7–5, 4–4 in MVFC play to finish in a tie for fifth place.
The 2015 Youngstown State Penguins football team represented Youngstown State University in the 2015 NCAA Division I FCS football season.
 They were led by first-year head coach Bo Pelini and played their home games at Stambaugh Stadium.
 They were a member of the Missouri Valley Football Conference.
 They finished the season 5–6, 3–5 in MVFC play to finish in a three way tie for sixth place.
The 2012 Youngstown State Penguins football team represented Youngstown State University in the 2012 NCAA Division I FCS football season.
 They were led by third year head coach Eric Wolford and played their home games at Stambaugh Stadium.
 They are a member of the Missouri Valley Football Conference.
 They finished the season 7–4, 4–4 in MVFC play to finish in a tie for sixth place.
Carl Pelini (born July 15, 1965) is a former head coach for the Florida Atlantic Owls football team.
 He is currently the Defensive Coordinator and linebackers coach for the Youngstown State Penguins.
 He is the older brother of former Nebraska and current Youngstown State head coach Bo Pelini.