"This contract is the greatest ever given to a punter in the history of the National Football League," Raiders senior executive John Herrera told The Associated Press.
NFL Network's Adam Schefter reports that Lechler's deal is worth $16 million over four years, with $9 million guaranteed.
Without locking down Lechler before free agency begins Feb. 27, Raiders owner Al Davis would have been forced to choose between keeping Lechler or Asomugha, Oakland's other All-Pro -- and Lechler probably would have left.
Lechler, who made $1.5 million last season, has the highest career punting average in NFL history at 46.8 yards. He led the NFL last season with a 41.2 net average, slightly bettering the NFL record he set in 2007.
If Asomugha is tagged again, he'll receive a 20 percent raise to around $11.7 million. The Raiders tried to reach a long-term deal with the University of California product last year but couldn't do so.
Copyright 2009 by The Associated Press