Wisconsin must replace a legend; how have other Big Ten schools done it?

There is no denying the impact Bo Ryan has had at Wisconsin. Now, he?s poised to retire after the 2015-16 season, his 15th at the helm.

[ MORE: Bo Ryan announces he will retire after 2015-16 season ]

Prior to Ryan's arrival in Madison, Wisconsin had never won more than 22 games in a season. Ryan has averaged 25.5 wins in his 14 seasons, all of which saw his teams finish no worse than fourth place in the Big Ten. The Badgers have won at least 20 games overall and 10 Big Ten contests in all but one of the last 13 seasons. And the last two seasons have been remarkable, as Ryan led the Badgers to the 2014 Final Four and the 2015 national championship game.

Ryan would like long-time assistant Greg Gard to assume his throne. We shall see. No doubt, whoever follows Ryan will have big shoes to fill being the guy who follows THE GUY.

Let?s take a look at how eight successors to legendary Big Ten coaches who worked at least 12 years at their school with great success have fared since 1975.

The good news for Wisconsin and Ryan?s successor: The transition often has gone well.

Mike Davis for Bob Knight, Indiana. Knight won three national titles and 11 Big Ten championships from 1971-72 to 1999-2000 and became one of the sporting world?s looming personalities in 29 seasons, a larger-than-life icon. Stepping into that enormous shadow in 2000-01 was formidable for Davis, who was promoted from an assistant?s job at IU he held from 1997-2000. Davis went 115-79 in six seasons with four NCAA and an NIT bid. He earned a share of the Big Ten title in 2001-02 en route to guiding the Hoosiers to the national championship game. Indiana has won one Big Ten crown since and hasn?t returned to the Final Four. Davis never was embraced in Bloomington and left for UAB in 2006.

Bill Frieder for Johnny Orr, Michigan. Orr went 209-113 in 12 seasons at Michigan from 1968-1980. He led the Wolverines to three NCAA bids, going to the Elite Eight twice and finishing as NCAA runner-up in 1975-76. Orr also had two NIT bids before leaving for a prosperous run at Iowa State. Frieder was promoted from Orr?s staff to assume command and did well in nine seasons, producing four NCAA bids and two NIT appearances before being canned prior to Michigan?s run to the national title in 1989 after he had planned to leave for Arizona State after the season.

Mark Turgeon for Gary Williams, Maryland. Williams, who left a big-time legacy in College Park over a 22-year run from 1989-2011, going 461-252 with 14 NCAA bids. Williams won three ACC regular-season titles and one tourney crown. He also reached two Final Fours and won the 2002 national championship. Turgeon was hired from Texas A&M and has thrived, going 87-50 with an NIT and NCAA bid in four seasons. His 2015-16 team will be the Big Ten favorite.

Matt Painter for Gene Keady, Purdue. Keady went 493-270 overall, won six Big Ten regular-season titles and had 17 NCAA appearances, including a pair of Elite Eight runs, in 25 years from 1980-2005. The current Boilermaker boss spent a year as head-coach-in-waiting under Keady in 2004-05 after coaching Southern Illinois in 2003-04. Since then, Painter-who played at Purdue under Keady from 1989-1993–has gone 212-125 in 10 seasons with one Big Ten regular-season and tourney championship and seven NCAA bids.

Steve Alford for Tom Davis, Iowa. ?Dr. Tom? forged a memorable career at Iowa over a 13-year run from 1986-1999. Davis went 269-140 with nine NCAA bids and two NIT appearances. Alford was a former Indiana great who arrived amid great expectations in Iowa City after a good four-year stint at Missouri State. He had some success, going 152-106 in eight seasons with three NCAA and three NIT bids. But the program became stale under Alford, who bolted for New Mexico and gave way to the disastrous Todd Lickliter.

Lon Kruger for Lou Henson, Illinois. Henson led the Fighting Illini from 1975-1996, going 423-224 with a Final Four appearance, one league title and 12 NCAA appearances in 21 seasons. Kruger arrived in Champaign off a successful run at Florida from 1990-96 in which he took the Gators to the 1994 Final Four. Kruger?s stay at Illinois was just four seasons-but they were successful, as the Illini went 81-48 with a Big Ten title in 1998 and three NCAA bids. Kruger was off to coach the Atlanta Hawks, where he was fired in his third season season.

Tom Izzo for Jud Heathcote, Michigan State. Izzo was a loyal assistant to Heathcote from 1983-1995, who led the Spartans to a 339-221 record, three Big Ten titles, nine NCAA bids and the 1979 national title in 19 seasons from 1976-95. Izzo has gone on to become a legend, winning a national title in 2000 to go along with seven Final Fours, seven Big Ten regular-season and four league tourney titles in 20 seasons in East Lansing.

Eldon Miller for Fred Taylor, Ohio State. Taylor went 297-158 in 18 seasons in Columbus from 1958-76, leading the Buckeyes to the 1960 national title and runner-up finishes in 1961 and 1962. He also made the Final Four in 1968 and the Elite Eight in 1971 with seven Big Ten championships. Miller arrived from Western Michigan and enjoyed some success over the next 10 seasons, going 174-120. He led OSU to four NCAA bids and the NIT crown in 1985-86-his last year before leaving for a highly successful run at Northern Iowa.

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