The key with defenses is finding defenses that will face a lot of passing plays. Fantasy point-scoring events like interceptions and sacks occur exclusively on passing plays, and fumbles actually occur more on passing plays than running plays. Defensive touchdowns are difficult to predict, but they're also more likely to occur on passing plays with 53 pick sixes last year compared to only 33 scoop 'n scores.
One of the best ways to identify defenses that will face a lot of passing plays is identifying Vegas favorites, preferably home favorites. And obviously the lower the opponent's implied point total, the better the matchup for the defense.
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Houston and Arizona are two of the biggest favorites of the week, both are playing at home, and they're facing the two teams with the lowest implied totals in Vegas.
The case for Houston is that they're facing the team with the lowest implied total, Tennesee, and they're cheaper than Arizona across the board. The concern is obviously that they'll be without J.J. Watt. But even without Watt, Houston's defense is still much better than both the Detroit and Oakland defenses who scored 16 fantasy points combined against the Titans in the last two weeks. The pricing gap between Houston and Arizona on DraftKings is large enough that Houston is an easy choice there.
But on FanDuel and FantasyAces the pricing gap is small enough that it might be worth it to pay a bit extra for the Cards defense that ranks seventh in Football Outsiders' DVOA and fourth in their DAVE rankings, which factor in preseason projections to filter out some still existing sample size issues. Arizona will face the Rams who haven't been quite as friendly to oppsoing defenses as the Titans have, but every defense that has faced the Rams has scored at least eight fantasy points. Long story short: if you build a lineup with Houston's defense and have money left over at the end, you can use it to upgrade to Arizona.
Both teams are going to be popular options this week, so you might look elsewhere in GPPs.
Sneaky Option
This category is reserved for good defenses that may be overlooked in a given week for whatever reason, providing you with the opportunity to roster a really good unit with a lower ownership rate. The team that most fits that bill this week is Baltimore. The Ravens rank fifth in DVOA and third in the DAVE rankings, but they probably won't be one of the three most highly owned defenses this week. They could crack the top five in ownership rate on DK where they're priced very well, but they'll probably be largely overlooked on FD. There's no doubt that the Raiders present a tough matchup, but the Vegas variables still favor the Ravens D. Baltimore is a 3.5-point favorite at home, and the Raiders have a below average implied total of 21.5.
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Washington's defense is also in play for cash games on FD and Aces as they're cheaper than both Houston and Arizona on those sites. They're inexplicably more expensive than Houston on DK.
Washington’s defense is not good. They rank 25th in DVOA, which is in line with FO’s preseason projections for their defense. But the Cleveland Browns can cure a lot of ills. Each defense that has faced the Browns so far has recorded positive points on the week, and two of those defenses finished with double digit fantasy points. Washington really struggles to generate a pass rush, but Cleveland could be a cure for that problem specifically as they rank 30th in FO’s adjusted sack rate and have allowed at least three sacks in each game this season.
New England's defense is $100 cheaper than Washington's on FD, so perhaps Washington is really only the cheapest possible option on Aces. New England's D rates more favorably than Washington's in the DAVE rankings coming in at No. 16. They'll host the Bills who have the fifth lowest implied team total of the weekend.
One other cheap contrarian option on DK could be Pittsburgh. Pittsburgh’s defense is going to be more potent from a fantasy perspective as long as Pittsburgh’s offense does what it’s capable of doing. When Pitt’s offense puts up points like it’s capable of doing, the defense can end up seeing a lot of passing plays as the opposition plays catch up. FO’s DAVE rankings still rank Pittsburgh’s offense as the second most efficient in the league. If that holds, Pitt’s defense will be put in situations to score fantasy points. Those situations could happen this week with Pitt being a five-point favorite at home against Kansas City.