Благо отскок был высоким, смэш закончил розыгрыш.

Here благо is not the noun благо meaning good, benefit, or blessing. It is being used as a conjunction/particle meaning something like:

• luckily
• fortunately
• it was a good thing that
• sometimes since / seeing that

So Благо отскок был высоким means roughly Luckily the bounce was high or It was a good thing the bounce was high.

This use of благо sounds a bit literary or commentator-like, not the most neutral everyday wording.

Because Russian often uses the instrumental case after быть in the past or future when describing a quality or state.

So:

• отскок был высоким = the bounce was high

The adjective высокий becomes высоким in the instrumental singular masculine.

You may also sometimes see nominative after быть, but in sentences like this, instrumental is very common and natural. For a learner, the safest rule is:

• after был / была / было / были, predicate adjectives are often in the instrumental

Отскок means bounce or rebound.

In a sports context, it usually refers to how the ball came off the ground, table, wall, racket, etc. So отскок был высоким means the ball bounced up high.

It is a masculine noun:

• nominative: отскок
• genitive: отскока
• instrumental: отскоком

Here it is the subject of был.

Yes, смэш is a borrowing from English smash. In Russian sports language, it means a powerful attacking shot, especially in games like tennis, badminton, table tennis, and sometimes volleyball-related contexts.

In this sentence, смэш is a normal masculine noun and it is the subject:

• смэш закончил розыгрыш = the smash ended the rally

Russian often uses the name of the shot itself as the subject, especially in sports commentary.

That is a great question, because розыгрыш has more than one meaning.

Outside sports, it can mean things like:

• a drawing
• a raffle
• a prank

But in sports, розыгрыш often means:

• a rally
• an exchange of shots
• a play sequence

So here смэш закончил розыгрыш means the smash ended the rally.

The comma separates two clauses:

• Благо отскок был высоким
• смэш закончил розыгрыш

The first part gives the favorable circumstance, and the second gives the result.

So the structure is roughly:

• Luckily / Since the bounce was high, the smash ended the rally.

This is a normal use of a comma in Russian when a clause introduced by благо comes before the main clause.

Закончил is the past tense of the perfective verb закончить.

Perfective is used because the action is viewed as completed and with a clear result:

• the rally ended

That is exactly the kind of situation where Russian prefers perfective.

If you used the imperfective заканчивал, it would suggest something more like:

• was ending
• used to end
• was in the process of ending

That would not fit as well here, because the sentence describes one completed sports action.

It means the shot itself ended the rally, but in a very natural, compact sports style.

Russian often does this kind of thing:

• смэш закончил розыгрыш
• literally: the smash ended the rally

In fuller wording, you could say:

• Игрок закончил розыгрыш смэшем = The player ended the rally with a smash

So the original sentence is shorter and more vivid, which fits sports narration very well.

The word order is fairly natural and efficient for narration.

• Благо отскок был высоким sets up the helpful condition first.
• смэш закончил розыгрыш then gives the main event/result.

This order makes good sense in sports commentary: first the bounce, then the decisive shot.

You could rearrange parts for emphasis, but the given order sounds smooth and logical.