Merriman making presence felt

SAN DIEGO -- Here are five observations on the San Diego Chargers, based on camp practices of July 30:

1. For years, head coach Marty Schottenheimer opened training camp with the old Oklahoma drill, a physical eye-opener in which a defender has to beat a blocker and tackle a running back within an area lined off with pads. As the drill processed Sunday, the true competitive nature of the defense emerged. If tapes get back to opposing offenses, they might get a little scared.