Put yourself in the Chargers coaches' shoes: You have the NFL's best offensive player (LT), one injury to said player ruins your entire season and gets you fired (which happened anyway), and you just came off a season that saw a star player from your team get hurt in a meaningless game which you were chastized about endlessly (Brees; late on the 05 season). What would YOU do?
I dont think Cam feels it's nessisary to rest RB during the preseason. Especialy not with L.Book to spell him this season.
Your premise is good, but I think off the mark. I doubt injury was the reason they sat LT. They had the same QBs, OL, basic skill players, and coaches...LT is a proven commodity...they needed to look at his backup, not him.
The decision to sit LT is based on several things. His knowledge of the system in place (something that hasn't changed since his first year there), the coaching staff and systems being in place for multiple years there, and the fact that they knew he'd get plenty of touches during the year anyway. With that kind of proven talent, do you need to see more in preseason games ?? And the fact that even tho M. Turner had shown some good things with his play, they needed to see him more and his backups as well (who might never get downs during the regular season).
Here it is different. A new OL, a new QB, a new OC/system, new backup RBs, new skill set players in Ginn, Hakim, Campbell, Martin, Schlesinger, Mauia and of course the rest of the rookies... There are certainly more questions about this team, the offense in particular than with SD in the last 4 yrs...
That's why Brown may see more touches than LT did, even tho they are both their respective starting RBs...