The stats posted by the OP are correct, according to the latest NCAA report.
However, the report measures six-year graduation rates for student-athletes who were freshman from 2004-2007. It is a little early to assign credit/blame to Fred and Fran for these numbers.
Then that absolutely makes sense. McD and Morgan didn't graduate anybody. Let's just take a look at the guys Fred has coached:
2010
Diante Garrett: Don't know, only coached him his senior year and I don't see anything on cyclones.com so I assume he didn't graduate.
Jake Anderson: already graduated from N. Illinois.
Ejim: Graduated
Calvin Godfrey: Kicked off the team
Eric McKnight: Transferred
DeMarcus Phillips: Transferred
Jordan Railey: Transferred
Chris Babb: Graduated
Royce White: 1st round NBA draft pick
Anthony Booker: Graduated
Chris Allen: Graduated
2011
Korey Luious: Graduated
Will Clyburn: Graduated
Tyrus McGee: Graduated
Bubu Palo: Graduated
Percy Gibson: Transferred
Tavon Sledge: Graduated
2012:
Kerwin Okoro: Transferred
(Everyone else still at ISU)
2013: DeAndre Kane: Already graduated
2014: BDJ: Already graduated
I only listed the guys who have played for Hoiberg and have completed their eligibility, transferred, or graduated.
By my count that is 20 African Americans who have played for Hoiberg who are no longer at ISU in one shape or another.
3 Already graduated, so I literally do not care what happens at ISU academically, as they already have a degree.
6 Transferred to another school in good standing, so they really aren't ISU's responsibility anymore and the NCAA agrees with me due to the changes they made to the APR.
9 Have graduated
1 May or may not have but fred was his coach for only 1 year of his academic career
1 was the 16th pick in the draft
ISU has also set multiple records for team GPA under Fred. However, ISU graduates players at a very good rate and using stats from before he got here isn't an accurate representation of the situation Fred has fostered on the academic side. I'm very pleased with how the program has performed there.