Unless most of the teams in your league carry a backup defense, more than half of the league should be available to you every week. Perhaps instead of playing one above-average defense every week, regardless of matchup, we should instead target the widely available waiver wire defenses with the best matchups in any particular week? You can always make exceptions if your rent-a-defense gets hot - heck, you might find a team worth starting all year by accident. Even if you don't, good matchups will continue to increase as more quarterbacks get injured or yanked as the season goes on. You can steal some points from bad weather come December. I'll list the startable fantasy defenses on most waiver wires each week and rank them.
**San Francisco, New Orleans, and Tampa Bay have great matchups but are assumed to be rostered**
Denver (at Seattle)
The Broncos were probably drafted in a lot of leagues, but check in to make sure. They’ll face Geno Smith in a game that will likely see Russell Wilson stake his new team to a big lead against his old team. Smith isn’t as reckless with the ball as Drew Lock, but with Patrick Surtain II on DK Metcalf and the Seahawks breaking in a new left tackle (#9 pick Charles Cross) and right tackle (3rd round pick Abraham Lucas), the Seahawks quarterback will be put in some tough spots.
A Look Ahead: HOU SF @LV - The Texans coming to Russell Wilson’s home Denver debut? Yes, please.
Cincinnati (vs Pittsburgh)
The Steelers have a great set of skill players - including training camp sensation George Pickens, but they still have one of the worst offensive lines in the league and Mitchell Trubisky is starting at quarterback. The Bengals have a strong defense top to bottom, and they’ll be opening up their AFC Champion title defense in front of an energized crowd. Ben Roethlisberger threw multiple picks in each of the lopsided losses to the Bengals last year.
A Look Ahead: @DAL @NYJ MIA - The Cowboys' offensive line is suspect, and the Jets are the Jets. Buckle up.