tread water

John GrishamのPlaying for Pizzaを読んでいます。イタリアなど初めてで、もちろんイタリア語も全く分からないフットボール選手のRickは色々ととまどうことが多い様です。
Carlo rumbled in from the kitchen in his starched white apron and chef's hat. Now, here is the center. Six feet two, at least 250 pounds, broad shoulders. But a slight limp. He greeted Rick warmly, a quick embrace, no kissing. His English was far below Nino's, and after a few words he ditched it and switched to Italian, leaving Rick to tread water.
水の上を歩ける訳はないので "tread water" は水たまりの上を歩いているのを連想しますが、上の箇所はそんな意味のはずはありません。辞書を引きます。
・Oxford English Dictionary: Fail to advance or make progress: men who are treading water in their careers
・Cambridge English Dictionary: to not be advancing in any way: I think she feels that she's just treading water in that job.
・Cambridge Dictionary of American Idioms: to be active but without making progress or falling farther behind Sales are about the same as last year, and the company is pretty much treading water.
Etymology: based on the literal meaning of tread water (to stay in one place in water by moving your legs quickly)
"tread water" の元の意味は立ち泳ぎですね。