In "League of Denial: The NFL, Concussions and the Battle for Truth," written by investigative reporters Mark Fainaru-Wada and Steve Fainaru, the NFL is portrayed as an organization that exerted its influence in an attempt to sweep aside independent research and fund studies of its own on the cumulative impact of hits on the football field.
The authors write that the denials started in 1994 with then-commissioner Paul Tagliabue and continue today with present commissioner Roger Goodell.
The book noted that Tagliabue was responsible for forming the NFL's Mild Traumatic Brain Injury Committee and the league continually cited research that claimed "NFL players were impervious to brain damage." The committee asserted that concussions were minor injuries that did not lead to long-term problems with the brain.
"Tagliabue dismissed the matter as a 'pack journalism issue' and claimed that the NFL experienced 'one concussion every three or four games,' which he said came out to 2.5 concussions for every '22,000 players engaged,'" one excerpt of the book claimed.
In late August, the NFL reached a settlement in the concussion lawsuit involving more than 4,500 retired players or a proposed $765 million. But the league did not admit it was at fault.
The NFL did not cooperate with the authors on the book. League spokesman Greg Aiello declined comment on Wednesday.
The authors said they conducted more than 200 interviews and pored over thousands of pages of documents.
---New England Patriots tight end Rob Gronkowski has yet to play this season and still isn't sure when he'll be on the field, but he emphasized there's no pressure from the team to hurry back.
Gronkowski has been practicing on a limited basis as he recovers from forearm and back injuries.
"It's going good," Gronkowski said. "I'm progressing every week, feeling better every week, getting stronger every week, getting in better condition every week. So I'm still sticking to the motto day by day."
The Patriots appear to be proceeding cautiously with Gronkowski since he returned from fracturing the forearm near the end of last season and then hurt it again.
He remains questionable on the Patriots' injury report this week. New England (4-0) plays at Cincinnati (2-2) on Sunday.
"When I'm ready, I'm ready," Gronkowski said. "If it's this Sunday, next Sunday, the Sunday after that, it's just going day by day."
---Offensive tackle Levi Brown will be traded from the Arizona Cardinals to the Pittsburgh Steelers pending a physical.
Brown, owed more than $3.6 million, is signed through 2014. His salary next season is $6 million.
According to the website Pro Football Focus, Brown has played 269 plays and graded out poorly as a pass blocker but very well in run-blocking.
The Steelers are hoping to upgrade over Mike Adams, who had a difficult time in one-on-one matchups with Minnesota Vikings defensive end Jared Allen and hasn't been great as a run blocker, either.
Brown was a first-round pick (fifth overall) in 2007 and was with the Cardinals when current Steelers offensive coordinator Todd Haley held the same job in Arizona (2007-08). His learning curve should be rapid. The Steelers are entering their bye week and return to the field Oct. 13 for a road game at the New York Jets.
---Wide receiver Tiquan Underwood signed with the Tampa Bay Buccaneers after Tuesday's release of Kevin Ogletree.
Underwood played at Rutgers under coach Greg Schiano, now at Tampa Bay's helm. He was drafted by the Jacksonville Jaguars in 2009 and spent time with the New England Patriots and Buccaneers. While with the Patriots in 2011, he was on and off the active roster in the regular season and was released the day before Super Bowl XLVI.
Also, wide receiver Chris Owusu was signed to the active roster, revamping the receiving corps for rookie starting quarterback Mike Glennon.
---San Francisco 49ers running back LaMichael James used Twitter this week to vent his frustration over playing time this season.
With Frank Gore entrenched as the starter and Kendall Hunter as his backup, James was inactive for the 49ers' first three games. He had three carries for zero yards against the St. Louis Rams in Week 4.
"Some things I just don't understand at all I don't work at State Farm I'm not trying to be insurance," James tweeted.
He later deleted the tweet but added, "I don't tweet bout football on anything to my team so don't need ur input."
James, 23, played in four regular-season games last season and had 125 yards rushing on 27 carries and three receptions for 29 yards.
---The San Francisco 49ers announced they have signed former Arizona quarterback John Skelton to a one-year contract.
Skelton, 25, spent three seasons with the Cardinals and started 17 games, posting an 8-9 record. He was waived by the Cardinals on April 1 and picked up by the Cincinnati Bengals. But he failed to survive the final round of cuts in training camp with the Bengals.
With Arizona, Skelton completed 320 of 602 passes for 3,707 yards and 15 touchdowns. Last season, he was 109 of 201 for 1,132 yards and two touchdowns in seven games.
The 49ers released seventh-round draft pick B.J. Daniels on Monday. If Daniels clears waivers, the 49ers could add him to their practice squad.
Skelton is expected to compete with Colt McCoy for the backup quarterback job behind starter Colin Kaepernick.