At this point, we know that if Kellie thinks a player is ready for game time, that player will get minutes. So, the indication is that Kellie has not considered injured Tess, Rennie, and Emily ready for games against tougher comp. She sees them in practice everyday; all us arm chair coaches don't.
Also, Player "X "(who hardly plays) does not make many mistakes is a tricky rationale. If Player X had more time on the court, the mistakes might add up quickly. The coaching staff see everyday in practice what kind of decisions players make under pressure; how effective they are in executing plays; matching up under different defensive schemes. If Kellie is not calling a player's number, I would infer that player is not ready for prime time.
Now, I do hope that Tess and/or Rennie get healthy, make the development leap etc. needed in the very near future because this team desperately needs more outside shooters.