Why? Well, collectively the Michigan run game was nonexistent in U-M's annual spring played on Saturday. Combined, Blue and Maize running backs ran for 89 yards on 39 carries, good for a 2.3 yards per carry average.
"It's been improving," Harbaugh said. "It's the thing that always takes the most time.
"For example, pass protection has been good. It was good today. I know we got good players up front. That shows up in pass protection."
Besides De'Veon Smith's 50 yard run on Maize's opening play, the longest run came from Derrick Green on a 8-yard run.
"The run game takes a little more time," Harbaugh said. "Blockers are working combination, and that's a process. It takes some time."
Being that it was a spring game, Michigan was playing with split unit. And Harbaugh made note of that in the post game.
"You add it into a spring game, you shuffle the deck," Harbaugh said. "The 1s, who have been playing together, two are one team, three are on the other. Two of the 2s are one team, three on the other, and so forth -- that adds to it."
In the long run, Harbaugh maintains it's a process, and Michigan will continue to work towards the run game he covets.
"The running backs need to in this process to run behind the line," Harbaugh said. "And we continue to improve that process."
He hopes anyways.
Michigan next plays at Utah on Sept. 3.