For the seventh consecutive year, the Dallas Cowboys are the NFL’s most valuable franchise, according to Forbes magazine.The magazine puts a value of $2.3 billion on the Cowboys, who recently completed a 25-year, $500 million stadium naming rights deal with AT&T. The Cowboys were one of five teams to post double-digit percentage gains in value from a year ago, along with the New England Patriots, Houston Texans, Atlanta Falcons and St. Louis Rams.As a league, the NFL total value rose 5 percent with an average value of $1.17 billion for each of its 32 franchises. Brady hurts kneePatriots quarterback Tom Brady suffered a left knee injury when he was knocked down during a joint practice Wednesday with the Tampa Bay Buccaneers.Bucs defensive end Adrian Clayborn pushed Patriots left tackle Nate Solder into Brady, who went down and immediately grabbed his left knee. Brady, a two-time MVP, walked off the practice field and did not return.ESPN reported the MRI on Brady’s knee was negative and that his availability is considered day-to-day. A person with knowledge of the injury told The Associated Press it was a sprained knee.Brady tore a ligament in his left knee in the 2008 season opener and missed the rest of the season. He has played every game since returning.Briefly • Dolphins: Kicker Dan Carpenter was released after five seasons in Miami. Carpenter was set to earn $2.675 million this season. The Dolphins will go with Caleb Sturgis, the fifth-round pick out of Florida, who made both field goal attempts against Jacksonville, including a 58-yarder. • Rams: Linebacker Jo-Lonn Dunbar was suspended for the first four games of the season for violating the league’s performance-enhancing substances policy. The sixth-year player from Boston College played his first four seasons in New Orleans. • Bills: Quarterback Kevin Kolb, a Stephenville High School graduate, will start Friday night against Minnesota. Kolb didn’t play in the preseason opener after hurting his knee slipping on a rubber mat. • 49ers: Defensive end Demarcus Dobbs was suspended one game for violating the NFL’s substance-abuse policy. Dobbs was arrested for DUI and marijuana possession last November. • Broncos: Linebacker Von Miller was arrested Sunday for failure to appear in court on careless driving, driving without a license and driving without proof of insurance charges. ... Pro personnel director Tom Heckert will return to work Thursday after a month’s suspension for a DUI arrest. • Redskins: Veteran receiver Devery Henderson, who was signed in June after spending nine years in New Orleans, was released.