I think the answer to your question is: strength of schedule. Some of the teams they played, especially Richland Springs, are not too shabby.
Before you knock Granger's ranking system, take a look at MaxPreps.com. There are a couple of teams that are flip-flopped between the two ranking systems, but FEAST is pretty much in the same place on both of them. And considering that MaxPreps.com doesn't have any information about the teams in T-CAL, nor does it consider past records (they don't start ranking teams until three games into the season) . . . FEAST looks like they're about where they should be.
But it stands to reason that they should drop if they lose more games from this point on.
These ranking systems are entertaining, but so many factors play into the process. A couple of guys get hurt, a couple of guys who were hurt come back to play, a rainstorm strikes and a passing offense gets shut down by weather, a long road trip . . . that's why the games are played, right?