Inside Slant: 49ers' personnel losses in perspective

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Conspiracy theorists are circling the San Francisco 49ers, who were stunned Friday by their fourth retirement of the offseason. Right tackle Anthony Davis said he wanted to let his "brain and body heal," adding to a list of departures that also includes defensive lineman Justin Smith, linebacker Patrick Willis and linebacker Chris Borland.

It might be some time before we fully understand why so many key players have abandoned this franchise. (Yes, "coincidence" is among the likeliest explanations.) But as NFL teams move toward the obligatory part of their offseason programs -- five have mandatory minicamps this week -- it's worth putting the 49ers' exodus in perspective. Veteran players come and go from rosters each year, but based on one measure, no team has absorbed a greater net loss of personnel than the team that started it all off by parting ways with coach Jim Harbaugh in December.

The chart in this post is derived from a database of 2014 offensive and defensive snaps assembled by Henry Gargiulo of ESPN Stats & Information. Rather than simply providing a number of players signed or lost, it helps illustrate the impact of the transaction based on how often they played last season. You'll see that Davis' departure has pushed the 49ers ahead of the Miami Dolphins for the highest total of lost snaps.

But the final column of the chart offers better context. When you take the difference between snaps lost and snaps added -- a measure of what's left on the roster -- you find the 49ers atop the list with 5,697 net snaps lost. The Philadelphia Eagles are next (4,853), followed by the New Orleans Saints (4,271). No other team has more than 3,500 net snaps lost.

In addition to the four retirements, the 49ers allowed nearly a half-dozen veterans to depart via free agency: guard Mike Iupati, cornerbacks Chris Culliver and Perrish Cox, running back Frank Gore and linebacker Dan Skuta. Offensive lineman Jonathan Martin and receiver Stevie Johnson were released.

(The 49ers did acquire free-agent receiver Torrey Smith and defensive lineman Darnell Dockett, among others, but their arrivals only partially mitigated the 49ers' net losses.)

While we're at it, let's pull a few other notable nuggets from Gargiulo's database:

  • We know intuitively that NFL teams routinely move on from veteran players in favor of less experienced replacements, but these numbers provide stark data. All but four teams lost more snaps than they added, and the average loss was about 2,000 snaps per team.

  • Those figures make what the New York Jets did this offseason stand out to a greater degree. The Jets were the most active team in free agency by this measure (8,055 snaps added), followed by the Chicago Bears (6,328) and Oakland Raiders (6,179). But they also had the highest positive disparity between snaps added and snaps lost (3,975). No other team had more than 762 (Bears).

  • The Green Bay Packers' nihilist approach to free agency, except for the occasional Julius Peppers acquisition, can't be clearer. The Packers didn't sign a single player who participated in even one offensive or defensive snap in 2014. The Pittsburgh Steelers were next with 232 snaps added, and no other team added less than 1,641.

  • The Packers retained a league-high 95 percent of their 2014 offensive snaps, followed by the Steelers (94), Panthers (92) and Bengals (91). The offenses figuring to look the most different in 2015, based on snaps, are the Kansas City Chiefs (57 percent retained), Dolphins (61) and Denver Broncos (63).

  • The Minnesota Vikings (94 percent) and St. Louis Rams (93) retained the highest percentage of their defensive snaps. The 49ers have a league-low 61 percent of their 2014 defensive snaps on the roster, followed by the New York Giants (62) and the Houston Texans (64 percent).