Tā hěn huì kàn fēngxiàng, zǒngshì zhàn zài yíng de yī biān.
He's good at reading which way the wind blows and always sides with the winner.
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看风向 (kàn fēngxiàng) figuratively means to assess the political or social situation before acting. 风向标 (fēngxiàngbiāo) means both 'weather vane' and 'bellwether/indicator of trends.'