Right now it's health and experience. Zach Mettenberger's played in a few more NFL games than Mariota has, and though mobility isn't a strength of his, he isn't banged up like Tennessee's top draft pick. If Mettenberger starts, he'll be physically capable of performing at his best. Mariota, who suffered an MCL sprain last week against Miami, wouldn't have the same luxury.
I do. The Falcons will play more quality tight ends this year—including Greg Olson, whom they'll face twice—so they'll have to make adjustments in coverage. William Moore owned up to a few personal shortcomings after Thursday's loss, and Quinn said the issues on defense were mental, not physical. Those problems tend to be fixed by analyzing tape.
Kyle Shanahan recently said Justin Hardy is improving and will contribute in 2015 when he gives Atlanta the best chance to win. So I expect to see the rookie WR play at some point this year, but I'm not entirely sure when. Nick Williams, a similar receiver, has done well for himself; and right now, everyone else at the position is relatively healthy.
I wouldn't be surprised if the coaches gave Hardy a shot next week. I also wouldn't be surprised if they wait until the second half of the schedule to activate him.
Julio isn't 100 percent—few are at this point—but he seems to be recovering well from that nagging hamstring injury. Quinn said Jones didn't face any setbacks against the Saints, so he should be all set for Tennessee after a long week of rest.
He does. Since joining the organization, Quinn has been emphasizing how important it is to win the turnover battle. The Falcons have done a good job protecting the ball and forcing opponents to make errors; on Thursday, however, they struggled in that regard thanks to three lost fumbles. Quinn mentioned it's a "hard lesson to go through" when you have a bad turnover ratio, and I imagine they've already gone through the corrections needed to play sharper football on Sunday.