Flagg won't make plays that the casual fan will notice (at least not consistently), but he was solid throughout the game with his run fits. His value on the field and probably why Steele will keep Flagg on the field more than most fans care for is because Flagg seems to have a solid grasp of what the **** is going on out there.
Flagg at several points of the game was directing his fellow LBs as well as DL. In a few cases, it seemed Flagg moved his teammates into a position to make a play.
Until the other LBs are making game-changing plays, I don't know how Steele will be convinced to remove Flagg from playing meaningful minutes.