SANTA CLARA, Calif. — Jim Harbaugh could be going back to school.

Once he coaches the 49ers for an apparent final time Sunday against the Arizona Cardinals, Harbaugh is expected to accept an offer to coach his alma mater, the University of Michigan, according to Bleacher Report’s Jason Cole.

Michigan officials are believed to be in the Bay Area to formally present a six-year, $48 million offer to Harbaugh, who’s finishing out the fourth year of a five-year deal with the 49ers.

“That’s what everybody on staff believes is going to happen this week,” a source said in the Bleacher Report article, which cited two of Harbaugh’s assistants and a league source.

“Jim has figured out that his style is best-suited for the college game. His shtick works better with young guys who are gone after three or four years.”

The Raiders, however, are expected to make a bid for Harbaugh once the 49ers (7-8) wrap up their season against the Arizona Cardinals (11-4). Other NFL openings also could occur and bring more suitors for the 51-year-old coach.

While with the 49ers, Harbaugh’s regular-season winning percentage (.697) ranks fourth-best among those who’ve coached in the Super Bowl era, behind only John Madden (.763), Vince Lombardi (.738) and George Allen (.712).

Harbaugh’s reign with the 49ers has included two NFC West titles, three NFC Championship games, a Super Bowl berth and an overall record of 48-22-1, including a 43-19-1 mark in the regular season.

Despite such early success, Harbaugh and 49ers CEO Jed York could not agree on a raise nor extend his contract beyond 2015. Contract talks were tabled prior to this season, which both sides agreed to be a boom-or-bust year for a franchise that now hasn’t won a Super Bowl in 20 years.

Rumored conflicts with York and general manager Trent Baalke apparently paved Harbaugh’s exit, as York even acknowledged before the season that such tension existed and that it could be a positive.

When Harbaugh agreed to a deal (five years, $25 million) to leave Stanford after the 2010 season, he joined a 49ers franchise in an eight-year playoff drought under former coaches Dennis Erickson, Mike Nolan and Mike Singletary. The latter was replaced for the 2010 regular-season finale by defensive line coach Jim Tomsula.

Tomsula and defensive coordinator Vic Fangio are thought to be the 49ers’ top in-house candidates to replace Harbaugh. The 49ers’ hiring process must also include an interview with a minority candidate to satisfy the league’s Rooney Rule.

Prior to joining the 49ers, Harbaugh spent his first seven years as a head coach in the college ranks, first at the University of San Diego (2004-06) and then at Stanford (2007-10).

After playing at the University of Michigan under Bo Schembechler from 1982-86, Harbaugh enjoyed a 15-year playing career and broke into coaching in 2002 and 2003 as a Raiders offensive assistant.

Michigan State restructures defensive staff: In East Lansing, Mich., Michigan State football coach Mark Dantonio has restructed his defensive staff, promoting secondary coach Harlon Barnett and linebackers/special teams coach Mike Tressel to co-defensive coordinators and also making Barnett assistant head coach.

The school announced the moves Saturday.

Barnett and Tressel are filling the position left by former assistant head coach/defensive coordinator Pat Narduzzi, who left the Spartans to become head coach at Pittsburgh. Narduzzi will direct the defense in the Cotton Bowl against Baylor.