49ers make cuts, then lose starting running back Jerick McKinnon to ACL tear

Jerick McKinnon, the 49ers' starting running back, tore his right ACL Saturday and will miss the entire season.

Three hours before head coach Kyle Shanahan got the news about McKinnon, Shanahan was already fearing the worst.

“I'm not trying to make it the darkest moment in the world right now,” he said on a conference call with Bay Area reporters. “We hope we're wrong.”

They weren't.

McKinnon, 26, tore his ACL during a light, non-contact practice Saturday morning that was closed to the media. “It was the last play,” Shanahan said. “He made a cut on air. No one was around him. Just went down. Looked awkward.”

The 49ers signed McKinnon to a four-year, $30 million contract on March 14. He will earn $10.5 million this season, more than every player on the 49ers other than quarterback Jimmy Garoppolo and left tackle Joe Staley.

McKinnon played in just one game during the preseason - the opener against the Dallas Cowboys. He carried the ball three times and lost four yards. Three days later during practice, on Aug. 12, he made a cut on his right leg and crumpled.

McKinnon initially thought he injured his right knee. An MRI showed he merely strained his calf. He missed the rest of the preseason, but was on track to play Week 1 of the regular season.

“He was back from the calf,” Shanahan said. “Today was the first time we allowed him to practice with the guys. On the day of the game, he was out there doing routes and stuff with the other guys before the game. So, he has been running routes, but today was his first day back in live 11-on-11 drills.

“What was unusual was the timing of the injury. It was just a couple hours before the final (roster) cuts, so he's got to be part of our 53-man roster.”

Now, he's not part of the 53-man roster. He's on the Injured Reserve list. And the 49ers have an open roster spot. They can use it to sign a pass rusher, which they need. Or, they can sign another running back, such as Joe Williams. The 49ers released him Friday just one year after moving up in the fourth round to draft him.

Williams wouldn't replace McKinnon as the 49ers' starting running back, though.

Matt Breida might. He rushed 105 times for 465 yards and two touchdowns last season as the 49ers' No.2 back behind Carlos Hyde. This year, Breida missed most of the preseason after separating his shoulder against the Cowboys. But he practiced Saturday.

“He was in the same boat as McKinnon (Saturday),” Shanahan said. “Those guys got some work in with our quarterback on game day on Thursday. Today was their first day cleared 100 percent, ready to go. We didn't have pads and we didn't hit - we probably won't do that until Thursday. But yeah, he's good to go.”

Breida is a second-year player who's small for his position - 200 pounds. If the 49ers want a bigger, more experienced running back to start in McKinnon's place, they could go with Alfred Morris.

The 49ers signed Morris on Aug. 13. He played in two preseason games with the 49ers, rushed 19 times for 89 yards and made the final roster.

Morris played for the Cowboys last season. They did not re-sign him. In 2012 and 2013, he played for Kyle Shanahan, the Washington Redskins offensive coordinator at the time, and gained 2,888 rushing yards.

Morris always has had a terrific feel for Shanahan's outside-zone blocking scheme. He may even have a better feel than the other running backs on the 49ers, including McKinnon.

“Like Kyle mentioned, we're concerned, but also confident,” general manager John Lynch said on the conference call. “We've got a lot of good football players here. We're proud of our 53-man roster. And next week, we're going to be really excited to take on the Vikings.”

Also Saturday, the 49ers trimmed their roster to 53 players by the 1 p.m. deadline.

The team released 21 players, including defensive end Jeremiah Attaochu, who signed a one-year, $3 million contract during the offseason. At the time, the 49ers envisioned him as one of their primary edge rushers in the nickel defense, but the vision never became reality.

“Jeremiah was a guy we were excited about,” Lynch said. “Unfortunately, due to some injuries during camp, we just didn't get that many opportunities to correctly evaluate him. And as you go into the regular season, dependability in terms of knowing a guy is going to be out there is really important. And we just didn't have that feeling, and so we made a tough decision, but one we felt we had to make.”

Now, the 49ers know they need a pass rusher. They even tried to trade for All-Pro defensive end Khalil Mack before the Raiders sent him to the Chicago Bears in exchange for two first-round picks Saturday morning.

“We would have been foolish not to,” Lynch said. “We went in aggressively, but also knowing we had to set some parameters, and we did.”

The 49ers will continue to look for pass rushers the next few weeks.

“I mean, we looked into Khalil Mack,” Shanahan said. “We'll look into anything we feel can improve us.”