Jc23, Skywest is an airline. Airlines change a lot in two years.

SFO is a normal base (not reserve base) on both the CRJ and Bro. There are 35 guaranteed lines on the Bro there right now. SFO is also the 2nd most junior base on the bro right now behind PSP. FAT is typically the most junior base on the Bro but seems to have gone 'slightly' more senior when they reduced the lines.

At 6 months seniority on the bro someone would be a lineholder in PSP and SFO and have a composite in FAT. LAX is a bit more senior but you can pretty much hold a line anywhere on the Bro within a year.