Somewhere in the 163-page National Football League concussion settlement there is presumably help for Matt Blair, the former Minnesota Vikings All-Pro linebacker who is now 63 and has increasing memory problems.

Blair said he played through two concussions during his football days, although compared with some of his Vikings teammates he feels fortunate he can continue a freelance photography career. But he said his forgetfulness goes beyond what someone his age should be experiencing. “If someone tells me something right away, I just don’t remember it right away,” said Blair, who said he has not been medically diagnosed with a memory-loss disease. “I can feel it and know that it shouldn’t be that way.”

Critics of the settlement, which a federal judge in Pennsylvania tentatively approved Monday, said Blair is typical of many of the estimated 20,000 former NFL players who will be asked to endorse the plan: They will have to decide whether to accept it before knowing whether they will ever get a dime from it.

Chris Seeger, the co-lead counsel for the retired NFL players who are supporting the settlement, said however that Blair and others like him will also need to think about something else: If they opt out of the agreement, they will be on their own in trying to prove that any dementia or other brain trauma was caused by playing in the NFL. Under the agreement, any former player with an approved diagnosis will not have to show that the injury came from playing in the NFL.

“It offers [Blair] a lot,” Seeger, speaking from New Jersey, said of the settlement.

With the legal battle lines now drawn — and with former players having until Oct. 14 to opt out of the deal — lawyers are trying to sell the plan as the best deal they will likely get from the NFL, while other attorneys will be trying to amass enough opt outs to undermine the settlement.