Fantasy football research never stops, and roles change drastically from one week to the next. That's where our fantasy football mailbag comes into play.

Have a question about a certain player, team, strategy, or anything football? Shoot us a question on Twitter or send an email to Jim.Sannes@FanDuel.com, and we can talk anything fantasy football related -- even daily fantasy football.

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Now, let's answer some questions.

Email submission from Keenan Bates:

I am definitely starting Freeman this week, as he has a good match up at home against the Chargers. Here is the tricky part. I traded for Tevin Coleman so I could handcuff he and Freeman in ideal match-ups. But I also have Christine Michael, who played very well last week and is becoming a very solid RB1, but is facing a very stout defense in the Cardinals. I did some research and the over/under for the Falcons (-6.5)/Chargers game is 53.5 and the over/under in the Seahawks (+2)/Cardinals game is 43.5. So it seems like a prime opportunity to let Freeman and Coleman start in my line-up, but Michaels is playing like a stud and should get his opportunities in Arizona. Both are in domes, so no weather variables to consider, but I'm keeping tabs to see if there are any line changes. I had to reach out and get your take on who I should roll with for my second RB. Thanks again!

The thought process behind all of this (implied team totals, weather, spreads, etc) is exactly what we want to look for in running-back selection, so you've already done the right kind of homework here. There is one major factor, though, that favors Christine Michael over Tevin Coleman, and that's volume. It's also enough to swing the pendulum over to starting Michael.

In the three games with Thomas Rawls out of the lineup, Michael has at least 21 touches each time, and his snap rate has never been below 64.3%. Coleman's maximum number of touches in a game is 15, and his highest snap rate was 49.2% in Week 1. From a usage standpoint, Michael is the clear winner.

Michael's implied team total does put a cap on his upside, but we can depend on his floor. Even if the Seattle Seahawks fall behind, Michael has been involved in the passing game with 12 targets over the past three weeks, 9 of which have come since C.J. Spiller's signing with the team. Coleman's matchup is tempting, but Michael's involvement in the offense makes him the safer play.

As we've seen throughout the season, the New York Jets' defense is a lit match short of a dumpster fire, making Joe Flacco a tempting option. You can certainly use him, but Kirk Cousins is going to be hard to pass up.

While the Jets have been bad, they haven't been nearly as bad as the Detroit Lions. In fact, nobody has. The Lions are the worst defense against the pass, according to numberFire's metrics, and it's easy to see why after future Hall-of-Famer Case Keenum lit their secondary aflame in Week 6. Cousins has outperformed Flacco this year, ranking 14th in efficiency based on numberFire's metrics compared to the 29th-ranked Flacco, making Cousins the superior play this week.

Email submission from Jose:

Is it worth keeping Ryan Mathews, Arian Foster, or T.J. Yeldon on a roster anymore?

You can probably drop Arian Foster given the usage that Jay Ajayi saw last week, and Ryan Mathews is going to be hard to start on a weekly basis due to his low snap rate. There are, at least, still merits to T.J. Yeldon.

Just last week, Jaguars offensive coordinator Greg Olson said that Yeldon was the team's feature back over Chris Ivory. That absolultely did not pan out in Week 6 with Ivory out-touching Yeldon, 13-7, but Yeldon still played 62% of the snaps compared to 40% for Ivory. There's value in that, and it means Yeldon is still worthy of a roster spot.

The Jaguars' running backs are going to be hard to predict, meaning Yeldon will be completely frustrating. But there's still a chance that his role increases, in which case he'll be a guy you don't want to leave on waivers.

There is a way that you can talk yourself into loving Jamaal Charles this week, and it's not a hard one to buy. We'll get to that in a second, but first, let's discuss why Spencer Ware is the better selection at least for Week 7.

With Charles active in Week 6, Ware still played 62.5% of the snaps, turning 24 carries into 131 yards and a touchdown. The New Orleans Saints have numberFire's 32nd-ranked defense against the rush, and with the Kansas City Chiefs checking in as 6.5-point favorites at home, any carries Ware does get are going to hold a lot of weight. He's a bruiser on the goal line, giving Ware plenty of upside.

Here's the tinfoil hat version of this dilemma. The Chiefs didn't really need Charles to defeat the Oakland Raiders in Week 6, coasting to a victory in a sloppy mess. Why risk injuring one of the most efficient runners of all time in a blowout with atrocious weather?

Unfortunately for our collective sanity, the breakdown of usage supports this thought line. When the game was within one score, the touch distribution was nine carries for Ware to seven for Charles. When the Chiefs' lead was 9 points or larger, Ware had 15 carries compared to two for Charles. If the game were to be closer Sunday, Charles' usage could certainly increase, making this a more interesting discussion.

The thing we must keep in mind here is that we'd be acting on a hypothetical. Until Charles' role changes in a tight game, we should assume that Ware is going to get a higher percentage of the carries, making him the better play of the two.

Want to have your questions answered in our mailbag? Submit your questions by tweeting @numberFire or sending an email to Jim.Sannes@FanDuel.com.