Ok, now that there are a pretty decent number of recorded battles at the Relatively Low tier of proc rates, it's time to look at what they're saying collectively.
At this point it might as well be confirmed fact that not only is your center card (Card 1) much more likely to proc than any of the other cards, but it should also be noted that if it doesn't, your odds of getting a three proc seem to be far less, and for that matter, if the center card doesn't proc first, it won't proc at all. In over 600 battles, this has been true.
I'll be regularly coming back to add the other deck runs, and other information if anyone has suggestions on what else to include.
So far, results seem to indicate nothing much other than what most people should already know or should have observed by now. Card 1 will always proc the most often, if it doesn't proc first it won't at all, if it doesn't proc at all a three proc is much less likely, and there is no correlation between position outside of the center card that affects proc rate, at least not at this level. Outside of that, it seems to indicate (although I don't want to say it's definitive) that there's virtually no difference whatsoever between the proc rates for a skill 3, and a skill 1 card at this usage level. Furthermore, Relatively Low might be taken to mean (at least temporarily) that your proc rate is just under or around 30%.