The input of the (Big) battery is so miniscule (35MW out of 2GW) that it could have no major impact on the pricing. See the tiny brown blips at the bottom of the chart to get an idea of the scale.
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The articles that were linked make only suppositions to correlation of a price decrease since it's installation. Not Causation. I think what probably happened is that it did open the eyes of the gas plants that if they kept gouging, they would open the door for investors to cash in on the current predicament of too much % of unreliable intermittents by building 20 more batteries.
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Correlation is not causation.
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