kono supuritto de abereezi ga sagatta.

Here, で shows the cause, reason, or occasion for what happened.

So この スプリット で アベレージ が 下がった means something like:

• Because of this split, the average dropped
• My average went down on account of this split

In sports contexts, で often connects an event to its result. It is not the location marker here.

が marks the thing that changed.

In this sentence, the thing that went down is アベレージ. So:

• アベレージが下がった = the average dropped

This is very natural with verbs like 下がる, because 下がる is an intransitive verb: something goes down by itself, rather than someone actively lowering it.

This is a very common question.

• 下がる = to go down, to fall, to drop
• 下げる = to lower something

So:

• アベレージが下がった = the average dropped
• アベレージを下げた = someone lowered the average

In this sentence, the average is treated as the thing that decreased, so 下がった is the correct choice.

この directly modifies スプリット.

So:

• このスプリット = this split

This follows the normal Japanese pattern:

• この + noun
• その + noun
• あの + noun

You cannot normally say この by itself before で here; it needs a noun after it.

They are loanwords, borrowed from English:

• スプリット = split
• アベレージ = average

Katakana is commonly used for:

• foreign loanwords
• technical terms
• sports vocabulary
• words the writer wants to emphasize as foreign-sounding

In sports, especially bowling, baseball, golf, and similar contexts, katakana vocabulary is very common.

In this sentence, スプリット is most likely the bowling term split.

A split in bowling is a difficult pin arrangement left after the first ball. Because splits are hard to convert, they can hurt a player's score, so the sentence naturally means that this split caused the speaker's average to go down.

So the sentence sounds like something a bowler might say.

Yes, the sentence leaves that unstated.

Japanese often omits information that is clear from context. So アベレージ probably means something like:

• my average
• his average
• our average

depending on the situation.

A more explicit version could be:

• 私のアベレージが下がった = my average dropped

But if everyone already knows whose average is being discussed, Japanese usually leaves that out.

Yes. 下がった is the plain past form of 下がる.

So it means the drop already happened:

• goes down / drops → 下がる
• went down / dropped → 下がった

This does not necessarily mean distant past; it just means the event is completed from the speaker's point of view.

Because Japanese is basically a verb-final language.

The core structure here is:

• このスプリットで = because of this split
• アベレージが = the average
• 下がった = dropped

So the verb comes at the end, which is normal Japanese word order.

Sometimes literally, yes, but in natural English because of is usually better.

A very literal breakdown might suggest:

• with this split, the average dropped

But in natural English, that sounds odd unless the context is very specific. So a better translation is usually:

• Because of this split, the average dropped
• This split brought my average down

So で does not always map neatly to one English word.

Both exist, but they are used in different contexts.

• 平均（へいきん） = average, mean, average value in a general sense
• アベレージ = average, especially in sports or performance statistics

In a bowling context, アベレージ sounds very natural.
If you were talking about math, test results, or general statistics, 平均 would often be more likely.

Normally, standard Japanese is not written with spaces like this.

The sentence would usually appear as:

このスプリットでアベレージが下がった。

Spaces are often added in beginner materials to make the sentence easier to read. They are a learning aid, not standard spelling.