ばかりだ details

write + only keeps getting worse

kaku bakari da

only keeps getting worse; and, once everything is prepared, all that is left is to do it

薬くすりを飲のんでも、症状しょうじょうは悪わるくなるばかりだ。

kusuri o nonde mo, shoujou wa warukunaru bakari da.

Even with the medicine, the symptoms only keep getting worse. neutral

書類しょるいはそろった。あとは判はんを押おすばかりだ。

shorui wa sorotta. ato wa han o osu bakari da.

The paperwork is all together. All that's left now is to stamp it. neutral

Examples

only keeps getting more so — a change running one way, with no sign of turning back

薬くすりを飲のんでも、症状しょうじょうは悪わるくなるばかりだ。

kusuri o nonde mo, shoujou wa warukunaru bakari da.

Even with the medicine, the symptoms only keep getting worse. neutral

練習れんしゅうをさぼってたら、下手へたになるばかりだよ。

renshuu o sabottetara, heta ni naru bakari da yo.

If you keep skipping practice, you'll only get worse at it. casual

対策たいさくを取とらなければ、被害ひがいは広ひろがるばかりです。

taisaku o toranakereba, higai wa hirogaru bakari desu.

Unless measures are taken, the damage will only continue to spread. neutral

all that is left is to do it — every preparation is finished, and only this one act remains

書類しょるいはそろった。あとは判はんを押おすばかりだ。

shorui wa sorotta. ato wa han o osu bakari da.

The paperwork is all together. All that's left now is to stamp it. neutral

荷造にづくりは終おわったし、あとは出でかけるばかりだよ。

nizukuri wa owatta shi, ato wa dekakeru bakari da yo.

The packing's done, so all that's left is to head out. casual

会場かいじょうの設営せつえいは完了かんりょうし、あとは開演かいえんを待まつばかりです。

kaijou no setsuei wa kanryou shi, ato wa kaien o matsu bakari desu.

The venue is fully set up, and all that remains is to wait for the curtain to rise. formal

ばかりになっている — for the "one step left" reading — everything else is done and the situation stands ready: 荷物にもつは送おくるばかりになっている.

In the "one step left" reading the sentence usually names the finished
preparations first — 準備じゅんびは終おわった。あとは出でるばかりだ。

一方だ
一方いっぽうだ states the direction and nothing more, so it can report a rise the speaker welcomes (売うり上あげは伸のびる一方いっぽうだ); ばかりだ carries the speaker's resignation, which is why it is nearly always a worsening and sounds odd about good news.
ところだ
するところだ puts the act at the next moment on the clock; するばかりだ says nothing about when and everything about the preparations — every other step is finished, so this one is all that is left, and it can sit that way for weeks.

ばかり
The same ばかりだ after two different hosts — after a noun it restricts what there is (お菓子かしばかりだ "it's all sweets"), while a dictionary verb leaves 寝ねるばかりだ genuinely ambiguous, and only the surrounding clause settles it: a finished-preparations clause in front gives "all that is left", a で continuation gives "does nothing but".
たばかりだ
One form of the verb apart, and pointing opposite ways in time — 出発しゅっぱつしたばかりだ says the departure has only just happened, 出発しゅっぱつするばかりだ that everything is ready and it has not happened yet.