Who knows when he'll even play. Not as exited as some people here seem to be. He made some nice tackles when he guessed right but McKinney should be the starter with no problem.
He's limited, no doubt there, but in short yardage situations and goal-line, even if you put him at just 40% successful (Which is not correct, because he was far more successful), he did something that few teams have, a player that in crunch time situations, single handedly stopped the RB.
I doubt he is being thought of as a starter, but even if he is, Coach Flores does not put people out there just because he likes them. Produce, and you start, so Roberts will be a situational and backup LB...No more, but what he does do, or just throwing his body out there to make plays is much needed on any team.