After all the games are played, I would image that all the schools will play some terrible teams that brings down their RPI.  MA will play Surry Central and Forbush who are bottom of conference teams.  Shelby plays Highland Tech and Cherryville.  Again, after more games are played, the RPI tends to get more accurate.  What is hurting Shelby right now is their loses in games.  Once they run the table in conference, their RPI will greatly improve.  
RPI formula was also modified this year to: RPI = (.4 x WP) + (.4 x OWP) + (.2x OOWP).  
If you look at the RPI or the seeding by GrizzleDevil, some of these teams that are seeded high, have no business even having a home game, but because they are 3-0 or 2-1 against some weak teams, they currently have a high RPI.  I stated on another post, that I wouldn't even look at RPI until after week 7 (at the earliest).