Harbaugh took a 1 win team to 4, to 5, to 8, to 12. His situation was by far worse than Sark's. He had Tavita Pritchard playing QB his first two years. Locker is a polarizing guy, but Pritchard was basically Casey Paus II. He was terrible. Looking back, he probably should have played Luck his true freshman year, but Harbaugh may not have wanted to throw him to the wolves too early.
The other thing Harbaugh did was develop players. In 2008, he had the same WR's and TE's (Fleenor, Baldwin, the Whalen's, Owusu) as 2010. Young players got better under Harbaugh. I would have loved to see what he could have done at Michigan, they would have been scary good.