There is mounting speculation within the league that the Redskins might attempt to sign cornerback Aqib Talib when the NFL’s unrestricted free agent market opens at 4 p.m. It is unclear, however, whether the Redskins would be able to outbid the New England Patriots, Talib’s current team, and squeeze a big contract for him beneath the salary cap. The Redskins ranked 30th in the league in pass defense this past season and are in need of help at cornerback, especially after Monday’s release of veteran DeAngelo Hall. Talib has a connection to the Redskins because he formerly played for secondary coach Raheem Morris with the Tampa Bay Buccaneers. But Coach Mike Shanahan estimated Monday that the Redskins were only about $1 million beneath the salary cap and said the team will have to proceed cautiously in free agency. Redskins officials said Monday they’d abandoned hopes of regaining some of the $18 million salary cap reduction they must absorb this year in time for the opening of the free agent market.