In 2007 the Raiders got the following production out of their WRs:
Top 2 WR (Curry, Porter): 99 receptions for 1422 yards
Remaining WRs: 20 receptions for 254 yards
Some of that is the QBs, but only 20 receptions spread over 4 receivers says something about how poor the play at WR was. Porter has exercised an option to void the remainder of his contract and could be headed elsewhere (43% of receptions by a receiver departing with Porter or departed with Mike Williams, and UFA Tim Dwight accounts for 5%).
To say that the Raiders need help at WR is an understatement...