Someone from the official chargers website has done a better job than me of explaining why we won't be going after big names like Hamlin, or even Grant (who I want).
One of the reasons we're inactive in free agency is because we just don't have that much money left under the cap. Back on March 3rd we were at around $12.2 million under the cap. Since then we've signed Dielman, Withrow, and Floyd. That's another $8 million at least.
Everyone remembers that we were supposed to be over $20 million under the cap this offseason. And then everyone forgets about all the players we've signed. We've signed 14 players since the offseason began, including sizeable contracts to Dielman and Phillips and a high tender of $2.3 million to Michael Turner. (I think a lot of people are under the mistaken impression that Shaun Phillips contract is $17 million for 6 years. That's wrong. $17 million is what he's guaranteed. His contract is more likely pays him $4.5 to $5 million per year under the cap.)
The money goes quickly when you move quickly to retain players.
I would be surprised if we're more than $5 or (at the most) $6 million under the cap right now, and we know that AJ likes to keep $2 or $3 million available in case we need to acquire a player in an emergency, like when we got McCardell to replace Caldwell in '04.
We may be able to unload Turner's $2.3 million if we trade him. But beyond that we're pretty tight on money now. This is why I laugh when people say we've "done nothing" this offseason. That's wrong. We've signed a whole bunch of guys. We just aren't spending the money on other teams' guys.
Also, the league has reduced our salary cap number. While the salary cap is increasing to $109 million this year, our salary cap is less than $107 million.
We had a player or two earn some "unlikely to be earned incentives," money that was not accounted for under last year's cap but the player earned as incentives, and when that happens the number is deducted from the team's next-years salary cap availability. Our salary cap is $106.7 million for 2007, not $109 million.
Yes, I think our available money has become very lean indeed.