It was his rookie year with the Ravens, and he said he ran down the field straight into three offensive linemen. Team doctors kept him out of the game until he was more himself.
But that caution was not always the way for the Ravens or the National Football League, where McClain said players have embraced the ethic of playing through pain. That has trickled down to many youth leagues where the long-term damage inflicted by concussions has also been ignored.
Top officials with the Ravens and their doctors at MedStar Sports Medicine say they want to change the culture in area sports.
"When in doubt, sit it out," said McClain at the end of a new public service announcement filmed as part of an effort by the Ravens and MedStar to raise awareness about the long-term dangers of concussions and teach youth athletes, as well as their coaches, parents and teammates, how to recognize symptoms.
On Tuesday, the Ravens pledged $125,000 to a five-year campaign of education, research, clinical care and testing. This is in addition to millions pledged by the NFL for research and education about concussions.
"We've taken a number of steps to improve player safety," said Dick Cass, Ravens president, during a news conference at their training facility in Owings Mills. "But we recognize we need to do more."
The league has come under fire recently from former players and their families, who have signed onto a lawsuit claiming that officials did not provide enough information to those who suffered concussions and failed to care for them. Many now have continuing issues with pain and memory loss that they believe are linked to repeated blows to the head.
Ravens and MedStar officials say they want to send a message to youth athletes that concussions are serious and can have cause long-term problems.
The state does not keep statistics on concussions suffered by youth athletes, but 248,000 people under age 19 were treated in emergency rooms in 2009 for a sports-related nonfatal traumatic brain injury, according to the U.S. Centers for Disease Control and Prevention.
The numbers are higher than in years past, but that is likely because more injuries are being counted, said Andrew E. Lincoln, director of the MedStar Sports Medicine Research Center.
In response, the state has instituted new rules requiring school coaches be trained to recognize symptoms of concussions and parents be informed about them. Students also can't return to play after a suspected concussion until they have been cleared by a doctor.
The NFL has taken similar steps to minimize long-term effects to players.
Lincoln said these are good measures. And the Ravens' money will help pay for more baseline cognitive testing that will help doctors identify changes in abilities and behavior that will inform their decisions on returning players to the game. But most of the money will help MedStar educate more youth athletes and those who know them, he said.
"It's important for teammates to know the symptoms because half of kids who experience a concussion will not report them to their coaches," he said. "So we're trying to make this about the good of the teammate or team."
The most common symptom is a headache, but those with an injury could also have light sensitivity, as well as problems concentrating or with memory and even changes to their appetite, said Dr. Andrew Tucker, the head team physician for the Ravens.
Most parents and others still learn about the symptoms after an injury and maybe not in time to stop an athlete from returning to the field, he said.
Changing the culture won't be easy, said McClain, who once was fined by the NFL for a particularly hard helmet hit he made on another player. But he said he now he wants to "work smarter" and be a role model for young players.
"We have a mentality of being a warrior," he said. "But now, the message is 'It's time for you to sit it out. There will be another day. You'll have another chance to fight.'"