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Last week's edition of Reading the Defense contemplated surprises among the top 25 scorers among fantasy defensive linemen and linebackers as well as highly drafted players surprisingly absent from those lists on Footballguys.com. After four weeks, Footballguy Adam Harstad has found that preseason ADP and in-season results are roughly equally predictive of end-of-year finish.

In 2013, Harstad wondered how many weeks into the season would pass before to-date scoring became more similar to year-end finish than preseason ADP. His analysis of the 2012 season and several subsequent seasons fairly consistently concluded upon an answer around the quarter-pole of the NFL season.

Harstad conducted his analysis only for skill-position players. Average draft position for individual defensive players is far less similar from source to source than that for offensive players, so parallel analysis is futile.

This week's edition of the column covers defensive backs. No position on either side of the line of scrimmage presents more uncertainty to preseason rankers and drafters. Defensive backs' roles can change from week to week or even in-game. The margins between the top players and replacement-level options are the thinnest in most scoring systems.

Real Situations, Fantasy Value

As Footballguy Sigmund Bloom often opines, talent, situation, and opportunity are the three legs that support the stool of fantasy football value. Of these, situation is perhaps the most complex.

Team context that supports fantasy production informs "situation." Los Angeles defensive tackle Aaron Donald averaged nearly eleven quarterback sacks per season through his first nine years in the NFL. He collected just five in eleven starts during the Rams' stunning 2022 collapse. The number of quarterback pressures the team generated last year was by far the lowest since Pro-Football-Reference.com began reporting the statistic in 2018. The Rams again rank near the bottom of the league in generating pressure in 2023, and Donald is well off the pace necessary for a double-digit sack season.

Lavonte David played middle linebacker for the Buccaneers for the first four seasons of his career and made at least 139 tackles each season. When undersized rookie Kwon Alexander joined the team in 2015, David began to play the weak side more frequently. Alexander was the protected linebacker to whom Tampa Bay's over-front spilled tackles. Both linebackers played full-time every game in the 2016 season. Alexander collected 145 tackles to David's 87.

The performance of the team around almost any fantasy asset affects his production. A player's role, too, greatly impacts his opportunities to make plays. Defensive scheme furthermore influences statistical output. Two safeties that frequently play deep in zone coverage leave their linebackers a huge area of the field to patrol. With more ground to cover, these linebackers must make more tackles.

#FFIDP - Most efficient coverage schemes for LB tackling in 2022:

Cover-2: 16.7%
Cover-4: 15.1%
Cover-3: 14.6%
Cover-6: 13.4%
-- LB AVERAGE: 13.3% --
Cover-1: 12.2%
Cover-2 Man: 10.6%
Cover-0: 8.0%

This makes 4-straight seasons for Cover-2 as the most optimal LB scheme for IDP! https://t.co/LvAAeJYknK

— Jon Macri (@PFF_Macri) January 11, 2023

Defenders' Counteracting Situations

Surrounding talent, player deployment, and defensive scheme inform the situational value of defensive backs. Unfortunately, the three rarely work in concert to increase statistical production. Game flow can even alter situational value in-game. A box safety on a good team will have opportunities to make plays behind the line of scrimmage; however, if the team builds a huge lead, the defense will fall back into a two-high shell. The linebackers, rather than the safeties, will compile more tackles, as Pro Football Focus's Jon Macri reports above.

Linebackers are not immune from counteracting situations. The Bills are a predominantly two-high team. Their linebackers, however, have not been high-volume tacklers. Instead, the Bills' defense very effectively gets off the field. In Week 5, however, Terrel Bernard compiled 16 tackles while his unit played a season-high 82 snaps in a game the Jaguars controlled.

Five, six, and seven years ago, box safeties dominated defensive backs' leaderboards for fantasy points. Box safeties played the majority of their snaps in the second level of their defenses, providing run support and facing tight ends in man coverage. Since then, the use of both zone coverage and two-high shells has increased dramatically.

The increase in zone coverages concentrates tackles in the linebacker position at the expense of others, including safety. While a pre-snap two-high shell does necessitate a two-high coverage, it typically means the two safeties will operate interchangeably. Neither plays a majority of snaps in the box. Each safety neutralizes the other's fantasy value. All things being equal, both are replacement-level defensive backs in fantasy leagues.

The writer of this column has been tracking player deployment and defensive scheme tendencies that impact fantasy value for years. A spreadsheet record is publicly available here.

2023 Defensive Back Values by Prototype

The Slot Defender

Former Titan Logan Ryan could be credited with single-handedly breaking the stranglehold of box safeties on the DB leaderboard if not for prevailing defensive trends. Ryan played almost exclusively in the slot, an alignment which proved advantageous for rushing the passer. He scored 4.5 quarterback sacks to complement 113 combined tackles. He led the league in targets by opposing quarterbacks, driving his tackle total beyond anything reasonably expected from a career cornerback.

Ryan finished as the top overall fantasy defensive back in 2019 by Footballguys' scoring. Indianapolis's Kenny Moore II duplicated the feat in 2021. In 2022, Kansas City's L'Jarius Sneed became the third slot defender in three years to clear the milestone of 100 combined tackles.

Sneed finished as the second-overall defensive back in fantasy scoring last season. His success made him the overwhelming favorite to lead all fantasy cornerbacks in scoring in 2023. The problem with this logic was the risk that Sneed wouldn't play slot this season. Kansas City Defensive coordinator Steve Spagnuolo advised last summer that Trent McDuffie was as likely to occupy the role as Sneed.