A league source tells us that the Washington Redskins quietly extended the contract of receiver Santana Moss last month, creating nearly the same amount of cap space that was burned up when tackle Jon Jansen recently was cut.

Per the source, the Redskins converted his base salary of $3.7 million in 2009 and $4.3 million in 2010 into a signing bonus, less salaries of $745,000 this year and $968,500 next year.

The difference is a guaranteed payment of $6.28 million.

The new deal adds three additional seasons beyond 2010, at base salaries of $1.192 million in 2011, $1.4155 million in 2012, and $1.639 million in 2013.  But we’re told that the three new years automatically void at the end of the 2010 season.

So why were the new years added?  To allow the guaranteed payment to be spread over five years.

As a result, the total cap savings was $1.7477 million.  And the Jansen cap charge was $1.726 million.

There also was a benefit for Moss; he received all of his 2009 pay and most of his 2010 compensation now.