You keep repeating the same soundbites . The Abbasids ruled through predominanly Persian culture. The bureauracy of the empire was Persian, and has been documented by Arab historians at that time. Moreover, the Islamic Golden Age of science was dominated by mostly Persians. The capital of Baghdad was in fact founded by the Iranian empires. First the Parthians.
No, I am parroting well-established and hard-cold facts.
No, there was no "Persian culture" in sight.
It's a oxymoron as pre-Islamic "Persian" culture was built on stolen Semitic culture and civilization almost entirely.
No, Arab scientists were more numerous but Arabized and Islamized Persian scientists were second to the Arabs but that had more to do with geography than anything. Not that there were many other options other than Arabs and Persians dominating. After all the Turks were largely still inhabiting the empty steppes of Central Asia. So not really much competition.
Baghdad was founded by Caliph Abu Jafar al-Mansur in 762. Before that in the vicinity of Baghdad there were a village dating back to Babylonian times.
"Persian" culture first reemerge under the Azeri/Kurdish/Arab (or whatever they claimed to be) Safavids who ironically could not have done what they did without the Arabs either.
https://en.wikipedia.org/wiki/Safavid_conversion_of_Iran_to_Shia_Islam
Arab Shia Ulama
After the conquest, Ismail began transforming the religious landscape of Iran by imposing Twelver Shiism on the populace. Since most of the population embraced Sunni Islam and since an educated version of Shiism was scarce in Iran at the time, Ismail imported a new Shia Ulama corps from traditional Shiite centers of the Arabic speaking lands, largely from
Jabal Amil (of Southern
Lebanon),
Mount Lebanon,
Syria,
Eastern Arabia and
Southern Iraq in order to create a state clergy.
[37][38][39][40]Ismail offered them land and money in return for loyalty. These scholars taught the doctrine of Twelver Shiism and made it accessible to the population and energetically encouraged conversion to Shiism.
[34][41][42][43] To emphasize how scarce Twelver Shiism was then to be found in Iran, a chronicler tells us that only one Shia text could be found in Ismail’s capital Tabriz.
[44] Thus it is questionable whether Ismail and his followers could have succeeded in forcing a whole people to adopt a new faith without the support of the Arab Shiite scholars.
[36] The rulers of Safavid Persia also invited these foreign Shiite religious scholars to their court in order to provide legitimacy for their own rule over Persia.
[45]
Abbas I of Persia, during his reign, also imported more Arab Shia Ulama to Iran, built religious institutions for them, including many
Madrasahs (religious schools) and successfully persuaded them to participate in the government, which they had shunned in the past (following the
Hidden imam doctrine).
[46]
https://en.wikipedia.org/wiki/Safavid_conversion_of_Iran_to_Shia_Islam#Arab_Shia_Ulama
And the most damaging scholar in Islamic history was an Arabized and Islamized Persian named Al-Ghazli. His works are one of the main reasons for the backwardness of the Muslim world.