in flux
マー君のお話です。
Japanese ace Masahiro Tanaka will make historic money but questions abound
The level of uncertainty surrounding Japanese ace Masahiro Tanaka, considered by far the best free agent pitcher this offseason, continues to confound the entire baseball industry, from the agents trying to represent him to the teams wanting to sign him to the system that will determine where he ultimately lands.
All parties agree on only one thing: Tanaka is going to be the most expensive import in baseball history.
The status of the 25-year-old right-hander, who went 24-0 with a 1.27 ERA this season for the Tohoku Rakuten Golden Eagles, remains in flux largely because of the expiration of the posting-system agreement used to transfer players from Nippon Professional Baseball to Major League Baseball. Sources from both leagues told Yahoo Sports progress has been slow because MLB wants to lessen the amount of money going to the player's team in Japan while NPB seeks proper recompense for losing its best players. The posting fee gives the winning MLB team the exclusive right to negotiate with a player; if they cannot strike a deal, the fee is returned from the NPB team to the MLB team and the player heads back to Japan.
「事態は（まだまだ）流動的だ」などというときに用いられることが多いのが（remain） in fluxというフレーズです。
fluxそのものは「流動」「不安定」などの意味で、"a situation in which things are changing a lot and you cannot be sure what will happen"（LDOCE）と定義されます。これにinが付いて、そのような状態の真っ直中にあるということがつかめます。
うわさはいろいろとあるもののその去就はまだ流動的というのが現時点の状況です。なお、同辞書にはEverything is in flux at the moment.という例文があります。（UG）
