Ben Margot/Associated Press

Former NFL running back Brandon Jacobs doesn't think too highly of head coach Jim Harbaugh when the two were with the San Francisco 49ers during the 2012 season.

During an appearance on CBS Sports Radio's Tiki and Tierney, Jacobs said he thinks Harbaugh had "no idea" what he was doing:

"Jim, I had a lot of respect for Jim when I was there – before I got to know him. I enjoyed my time there, but we didn't see eye-to-eye. I knew a little bit more about football than what they led on."

Jacobs continued: "Going somewhere where they don't have route conversions into certain coverages was just absurd. They're just running routes in the defense, getting people killed. Size and strength is what they had, and that's why they won. Let's be real. They had great assistant coaches, but Jim didn't know what he was doing. Jim had no idea. Jim is throwing slants into Cover-2 safeties, getting people hurt. That guy knew nothing, man."

The one season Jacobs played with the 49ers the team reached the Super Bowl with an 11-4-1 record. He only appeared in two games for the team due to a knee injury suffered during training camp and later due to a suspension for a series of social media posts criticizing his lack of playing time.

Harbaugh was one of the NFL's most successful head coaches during his four-year stint with the 49ers from 2011-14. He compiled a 44-19-1 record with three straight trips to the NFC championship game in each of his first three seasons.

After parting ways with the 49ers following the 2014 season, Harbaugh returned to coach his alma mater at the University of Michigan and has posted back-to-back 10-win seasons.

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Jacobs retired from the NFL after the 2013 season. He played nine years, including eight with the New York Giants, and won two Super Bowl titles.