A prominent PLA-watcher has said DDG 173 suffered a fault with one of her gas turbines, which precluded her from taking part in the exercises with Russia but had no effect on her cruising capabilities since she cruises with diesel. I don't recall how credible he is at the moment, someone pitch in and remind me if possible.
Additionally, he says DDG 173 is currently back at base, waiting for a suitable time to return to the shipyard to conduct repairs, with plans to implement small upgrades since she's going to the shipyard anyway. He also says the ship is still within warranty period so the shipyard bears full responsibility but I'm not sure if he's joking or not.
Also, nice pic of DDG 174 leading a Sino-Russo formation.