Chris,
Hypothetical only: Regarding the injection wells, in a rocky, stratified formation, isn't it theoretically possible for the spatial relationship to be skewed by rock, gravel, etc. movement and therefore potentially "lock" thus throwing off the relationship with the time/injection rates? I remember doing experiments with my students and sometimes that exact thing would happen in their miniature environments. Of course, I could be wa-a-ay off, too!
Beth
PS - Maybe they're watching in Memphis, but only by peeking through their fingers? :)