Zack Moss or Devin Singletary? Matt Milano or A.J. Klein? Cole Beasley or some other option?
Look for these questions and more to be answered or at least addressed by the end of Monday evening, when the Buffalo Bills visit the Tennessee Titans.
Moss and Singletary are their running backs, with no clear-cut No. 1. Just when it looks like one of them might take over, the other plays more. And just because Zack Moss has gone from being inactive in Week 1 to playing more snaps and getting more carries than Devin Singletary in Week 5's 38-20 win over Kansas City, it doesn't mean Singletary will be buried.
In fact, it really doesn't mean anything as the Bills continue their mission to stay ahead of opponents' adjustments to their prolific offense.
Doing that means trusting more than just a small group to handle or catch the football. And it means being able to switch identities from week to week, like the New England Patriots have done for the better part of two decades under Bill Belichick, for whom Bills offensive coordinator Brian Daboll worked for 11 seasons.
"What our approach is since we've been here, we're going to try to do what we need to do to win a game," Daboll said. “And whatever personnel group of plays that we think, or matchups we think … we go this personnel if they do this, we go that personnel if they do that. That's always going to be an important part of how we go about game-planning and deciding to play the game. And that changes week to week, based on our opponent.
"There's a lot of guys on our team that we have confidence in, and it’s our job to figure out which way to best use them."
The same applies to all the defensive linemen, who work on a rotational basis.
So let's get to this week's list:
RB Devin Singletary
His playing time likely has less to do with his efficient average of 5.2 yards per carry than it does with his four fumbles. He fumbled twice in the opener, once the next week and once in Week 4, when he finished with a season-high 14 carries for 79 yards.
But on Sunday night at Kansas City, he played just 15 snaps and carried six times for 25 yards. At least he didn't fumble.
RB Zack Moss
After being inactive for the opener, Moss fumbled on his first attempt in Week 2, when he averaged just 3.25 yards on eight carries and 4.0 yards on two receptions.
But he hasn't fumbled since and has gradually worked his way back into the mix as a trusted contributor. Last week he played a career-high 74% of the snaps.
Still, he's averaging just 4.0 yards per carry compared to Singletary's 5.2 this season.
So who's No. 1?
The answer may be that there isn't an answer, only a game plan that favor one player one week and the other the next.
WR Cole Beasley
Not sure what gives here. Beasley is a slot receiver, which makes him pretty versatile and a tough guy to cover in the middle of the field, especially when defenses have to account for Diggs and Sanders and now, tight end Dawson Knox.
It's not like he's suddenly hit a wall, either. He had 11 receptions as recently as Week 3. So he can still get open and still catch the ball as well as ever.
DE Mario Addison
He turned 34 last month. Last week he was edged in snaps, 29-28, by rookie Boogie Basham, who was a healthy scratch the first three weeks.
Addison has 61 career sacks and 12 forced fumbles, but his production (four tackles, 1.0 sack) hasn't been there through five games this season.
LB Matt Milano
A hamstring injury forced the Bills to deactivate him for last week's game. The Bills have been extra cautious with injuries since the start of their offseason camps, so it will be interesting to see how many snaps Milano, who practiced without restriction on Thursday, will play Monday night.
He and fellow linebacker Tremaine Edmunds rarely, if ever, come off the field. But A.J. Klein has been perhaps the most underrated member of the defense since coming to the team last season, so McDermott and defensive coordinator Leslie Frazier might not want to push Milano too hard with the type of injury that's been known to linger for an entire season.