Fantasy football: Best and worst matchups at each position for NFL Week 12

Derek Carr is having a career year though the air, with 19 touchdowns and only 3 interceptions. Mark J. Rebilas-USA TODAY Sports

Matchups play a huge part in fantasy football managers' start and sit decisions. When choosing between two (or more) similarly talented players, the decision often boils down to this: Which one has the best matchup?

We use that word -- matchups -- a lot. But what, exactly, constitutes a favorable or unfavorable matchup?

This is where the "Matchups Map" comes in. Each week, I'll provide a schedule-independent method to determine strength of positional matchups, using the most recent, relevant data. Check back for updated numbers each week, including matchups highlights at each position -- both favorable and unfavorable -- based upon those statistics. For these purposes, we will use PPR (point per reception) scoring.

"Adj. FPA," or adjusted fantasy points allowed, reflects how far above or below a player's average that defense held opponents at that position. A positive number means that the matchup is favorable; a negative number means it is unfavorable. This is a teamwide analysis, so a plus-5.0 Adj. FPA to running backs would mean that the defense afforded its opponents' entire running back corps five additional points on average, which should be kept in mind when evaluating running-back-by-committee approaches. All data is from the past five weeks' NFL action.

Finally, a caveat: Matchups are only one ingredient in my rankings formula. Not every favorable matchup should be exploited; not every unfavorable matchup should be avoided. To get the most complete recipe for whom to start and sit, consult my weekly rankings.