Chargers and Raiders notes

The San Diego Union Tribune reports the Chargers are going to make it difficult for four of their restricted free agents to leave.

Receivers Vincent Jackson and Malcom Floyd, linebacker Shawne Merriman and left tackle Marcus McNeill will also receive the high tender. Any team that wishes to sign any of these players will have to surrender a first and third round pick to sign the players. Even if a team decides to swallow the high cost, San Diego would have the right to match the offer.

The only player who could possibly attract a first and third-round pick may be Jackson.

Jackson and McNeill were expected to get the high tender. Merriman and Floyd’s designations are a bit surprising, but the Chargers value both players.

• Backup running back Darren Sproles is not expected to be tendered, making him free to sign elsewhere starting Friday. The Chargers are still interested in signing him to a long-term deal.

The Union Tribune is also reporting that cornerback Antonio Cromartie could be traded to Detroit. The Chargers have been shopping him for weeks.

The Chicago Tribune reports that backup San Diego tight end Brandon Manumaleuna could attract interest on the open market from the Bears and new offensive coordinator Mike Martz. Manumaleuna played for Martz in St. Louis.

• Meanwhile, Oakland coach Tom Cable said he has no regrets about trading a 2011 first-round pick to New England for Richard Seymour. What else is Cable going to say about the franchise-tagged 30-year-old defensive end? Oakland has no choice but to stand behind Seymour.

• Also, Cable said what has been expected: It will be an open competition for Oakland’s starting quarterback job. Expect Bruce Gradkowski to have the edge over JaMarcus Russell heading into camp.