〜ばかりだ

(1) "only keeps ~ing", "does nothing but get ~" — a one-way, usually worsening change; (2) "all that is left is to ~" — everything else is ready.

Both senses take a dictionary-form verb. Sense (1) uses a change verb (増える, 下がる, 悪くなる) and sounds negative; sense (2) is usually set up by あとは and means only the final step remains.

Sense (1) for deteriorating trends; sense (2) when preparations are complete.

• V-dict (change verb) + ばかりだ (worsening trend)
• あとは + V-dict + ばかりだ (all that remains)
• 〜ばかりで、〜ない for the continuing form

1. 01

   彼の成績は下がるばかりだ。

   かれのせいせきはさがるばかりだ。

   His grades just keep dropping.

2. 02

   最近、仕事が忙しくなるばかりだ。

   さいきん、しごとがいそがしくなるばかりだ。

   Lately work only gets busier and busier.

3. 03

   物価は上がるばかりだ。

   ぶっかはあがるばかりだ。

   Prices only keep going up.

4. 04

   借金は増えるばかりで、減らない。

   しゃっきんはふえるばかりで、へらない。

   The debt only grows; it never shrinks.

5. 05

   準備は終わった。あとは出発するばかりだ。

   じゅんびはおわった。あとはしゅっぱつするばかりだ。

   The preparations are done. All that's left is to set off.

• 〜一方だ

  Same structure but neutral: can be positive or negative. Compare side by side

• 〜たばかりだ

  'Just did' (食べたばかりだ). Different meaning; note the た-form.

• 〜ばかり (only)

  'Nothing but' after nouns or て-forms: 遊んでばかりいる 'does nothing but play'.

• ✗

  成績はよくなるばかりだ。

  ✓

  成績はよくなる一方だ。

  Why

  ばかりだ cannot describe improvement; use 一方だ for positive trends.

• ✗

  借金が増えたばかりだ。(meaning 'keeps increasing')

  ✓

  借金が増えるばかりだ。

  Why

  With the た-form, ばかりだ means 'has just increased'. The trend meaning needs the dictionary form.

• ✗

  彼は文句を言うばかりだ。→ counted as this pattern

  ✓

  (This is the 'only does X' use, not the change use.)

  Why

  言う is not a change verb; here ばかり means 'does nothing but complain'. The change meaning requires 増える/減る/なる-type verbs.

Typical verbs: 増える, 減る, 悪くなる, ひどくなる, 下がる, 広がる, 遠ざかる. The idea that nothing counteracts the trend is often stated: 〜ばかりで、少しもよくならない. Related ばかり uses (〜たばかり, 〜てばかりいる, 〜ばかりか) are separate items; check the verb form.