The biggest story swirling around Tesla Inc. right now concerns Chief Executive Elon Musk’s sudden, if unsurprising, break with a leader who is as calm and unassuming as he is, President Donald Trump. The important story concerns what is happening far from these shores: China. Shipments from Tesla’s Shanghai factory fell by 15% in May compared with a year before, according to preliminary data from China’s Passenger Car Association. That marks eight straight months of declining output from Tesla’s single biggest electric vehicle factory, accounting for around 40% of its global capacity. These figures don’t break out which of those EVs get sold in China or get exported from there, but this trend is not Tesla’s friend. Through April, its share of China’s battery EV market had fallen by more than half over the past four years, according to data compiled by New AutoMotive, a UK-based research firm.