Learn Turkish: Diksiyonu kötü olduğu için her şey fiyaskoydu. - Because his diction is bad, everything was a fiasco.

The translation says 'Because his diction is bad', but the main verb (fiyaskoydu) is in the past tense. How do we know the first part is present tense?

The participle suffix -dık (seen here in olduğu) covers both past and present states. It can mean 'because it is bad' (an ongoing trait) or 'because it was bad' (at that moment). The main verb (fiyaskoydu) anchors the event in the past, but the translation uses 'is' because bad diction is usually an ongoing, permanent characteristic.

Why do we use olduğu için instead of just saying kötü için?

İçin (because of / for) requires a noun phrase. You cannot attach it directly to an adjective to mean 'because it is [adjective]'. Instead, we use the verb olmak (to be) and turn it into a participle with -dık. Kötü olduğu için literally translates to 'for the reason of its being bad'.

Why is there a -y- in fiyaskoydu?

Fiyasko ends in a vowel. When attaching the past tense suffix to a noun or adjective, you are actually attaching a shortened version of the old copula idi (was). To connect a vowel-ending word to this suffix, the i transforms into the buffer consonant -y-, making it fiyaskoydu.

I often see 'herşey' written as one word online. Why is it separate here as her şey?