Flynn had a recurring problem with tendinitis while at the Seattle Seahawks and Allen confirmed that it is still bothering him following his summer move to Oakland.
However, despite currently being sidelined with the injury, Allen was keen to stress that it isn't a big problem and should be easy to cope with if they are able to monitor it closely.
"It's hindered him a little bit. I don't think it's been a major factor when we've gotten into games. I just think it's one of those things that we've got to manage," Allen told The Associated Press.
"I don't want to make it out to be any bigger of an issue than it is."