ANN ARBOR, Mich. -- After Michigan lost to Ohio State on Saturday, Jim Harbaugh didn’t have much to say other than that his team needs to improve. The loss capped off an 8-4 regular season with losses to the Wolverines’ top rivals, as well as Penn State and Wisconsin. It also brought Harbaugh’s record to 1-6 against Michigan State and Ohio State.

“I thought our guys played with great effort. We gotta get better, we gotta get stronger, we gotta improve,” Harbaugh said. “We’re going to keep going on the same demanding, punishing path and keep improving, keep getting stronger.”

Michigan’s season started on a high note with 33-17 win against Florida, but it ended with two starting quarterbacks on the sidelines and the biggest comeback ever recorded by Ohio State in the rivalry.

The Wolverines saw starting quarterback Wilton Speight go down with a season-ending back injury in Week 4 against Purdue, starting wide receiver Tarik Black sustain a season-ending foot injury the week before against Air Force and eventually saw quarterback Brandon Peters sustain a concussion against Wisconsin.

Jim Harbaugh is now 0-3 against Ohio State. Dan Sanger/Icon Sportswire

A team that returned the fewest starters of any FBS program had no chance to sustain success with that injury list, and starting left tackle Grant Newsome, who was injured against Wisconsin in the 2016 season, sat out the entire 2017 season.

For all of that, there is reason for optimism.

Part of the reason this team was so young and lacked depth goes back to the 2015 recruiting class, when Harbaugh was hired only months before signing day. That recruiting class included only 14 prospects because of the uncertainty surrounding then-head coach Brady Hoke and coming off a 5-7 season.

Of the 14 signees in that class, four are no longer with the team. Of the remaining 10, only four are regular contributors or starters: safety Tyree Kinnel, running back Karan Higdon, tight end Zach Gentry and wide receiver Grant Perry.

Offensive line has been the biggest problem for Michigan, which only added three players to the position in the the 2015 class. Newsome was a part of that class, but his injury left only Nolan Ulizio and Jon Runyan, neither of whom have been able to sustain a starting role.

The other major area of concern is under center. Michigan signed two quarterbacks in that 2015 class. Gentry was almost immediately moved to tight end, and Alex Malzone has never seen significant time. That left Harbaugh and Michigan to roll with Speight, eventually sign graduate transfer Jake Rudock and John O'Korn and try to bring in quarterback recruits in the future classes.

Next season, Michigan is essentially only losing eight main contributors, including Speight, who announced he will seek a graduate transfer. The Wolverines will also lose O'Korn, running back Ty Isaac, fullback Khalid Hill, offensive linemen Mason Cole and Patrick Kugler, defensive lineman Maurice Hurst, and linebacker Mike McCray.

If defensive end Chase Winovich and defensive tackle Bryan Mone, both redshirt juniors, return for a fifth year, Michigan will return all but two starters on defense.

On the offensive side, if you consider Peters the starting quarterback, the Wolverines return all but two starters on that side as well. That includes getting Black back from injury and returning some young talent at receiver to help propel the offense forward.

That doesn’t guarantee Michigan a better season, but it certainly gives a lot more hope than there was heading into the 2017 season.

Michigan has seen what Harbaugh can do when he has a capable quarterback, so returning Peters, having a more experienced Dylan McCaffrey as the backup and adding in two quarterbacks from the 2018 class (Joe Milton, Kevin Doyle) should give the coaches more options to field a successful offense.

There is no question that this team needs to improve after a disappointing season, but the potential is there with a more experienced roster coming back. There was some grumbling about how this season went, but things don’t look all that bleak in Ann Arbor.