Setting aside whether psiontal has actually fallen that much in win rate against bronze, there's a number of other good options that require no shards (and work with no rares) that are fully unupped. I would recommend monodark (swapping the stiletto for another pillar/drain life/steal/etc if you don't have one) or antabow (swapping the arsenics for poisons if you don't have them).
I experienced that the amount of PsionDim-Decks in Bronze arena increased. Since your own dim shields are pretty useless against it, it can cause problems and probably a drop of win-rate. Since I wanted to upgrade a Psiontal for myself (and for Bronze/Silver) I will test the unupped deck today (as soon as I get home) and will probably post the results. Although I don't know if I will play a full set of 50 games.
FWIW when I did the unupped psiontal tests we had already reached a good deal of aether saturation in bronze. I find that psiontal actually beats most psion decks in bronze (i.e. without double draw) right out of the box due to the AI being more or less incompetent with fractal and therefore being able to just outrush them.
If you are finding that psiontal loses to psion-based aether frequently, I would highly recommend adding in a lobo or two or adding in some of the lightnings that are common in pvp psiontal decks. Both of those will go a long ways in tipping the scale in your favor against opposing psions. Of course, neither will help against the more traditional mono aether (which I find a lot more common than psion MA in bronze), but you should be beating that anyways unless it packs SoW (which isn't that common in bronze). SoW-based mono aether is just gonna be a loss barring RNG letting you outrush.
edit: On a totally unrelated topic, since nobody seems to be leaping at my request that someone besides me do some tests, I'm finally submitting FEVER to the thread. Still would love it if someone else took some full stats.
Tests are in bronze/upped (and are the exact same tests I mentioned in the deck's thread).
FEVER, By
ColorlessGreen, Submitted by
ColorlessGreenW: 99 L: 1 WR: 99.00% TTW: 9.13 EM: 4/99 EMR: 4.04% UEI: 2375.76 SSPH: 7.08