I think that you have a good grasp on how Nader Shah had reversed the situation in that he was all of those things: politically opportunistic, militarily strategic, and diplomatically gifted. To further conceptualize this, we can look at his maneuverings during his path to Shah.

In the mid 1720s, Nader played an important role in the defeat of Malek Mahmud Sistani, a main warlord in northeastern Iran who had emerged in the wake of the Afghan invasion. Nader was initially Sistani’s ally but soon turned against him, and his role in suppressing Sistani brought him to Tahmasp’s attention. Tahmasp chose him as the principal military commander to replace Fath Ali Khan, who was killed on the orders of Nader Shah in 1726.

Nader then assumed the title “Tashmasp-qoli” or “servant of Tahmasp.” His prestige increased as he lead Tahmasp’s armies to numerous victories including defeating the Afghans near Herat in 1729 and defeating the Afghans at Mehmandust in 1729. Tahmasp became finally established in Isfahan by the end of 1729, marking the real end of Afghan rule in Iran and many Afghan soldiers joined Nader’s army and proved helpful in many subsequent battles.

Nader then waged a successful campaign during the spring and summer on 1730 against the Ottomans to capture much of the territory lost during the previous decade. However, Tashmasp later pursued his own campaign against the Ottomans from January 1731 through January 1932. This campaign was disastrous and the Ottomans actually reoccupied much of the territory that Nader had just regained.

Learning that Tahmasp had relinquished much of the territory that he had regained, he returned to Isfahan and used the Treaty of Rašt as an excuse to depose Tahmasp from the throne in August 1732 and replace him with Abbas. During the period between 1732 and the end of 1735, Nader had a decisive round of victories against the Ottomans. Russia and Persia signed a defensive alliance in March 1735 which returned much of the territory conquered in the 1720s.

After this, Nader felt that he had secure enough prestige through a series of military (during the Ottoman-Persian battles) and diplomatic (through the treaties and alliances with the Russians) prestige to assume the throne himself.

Ultimately, I think it is a combination of the reasons that you have suggested in the original post. Nader idolized Genghis Khan and Timur, from their military prowess to their cruelty. He was incredibly opportunistic as seen with his maneuvering around Sistani and Tahmasp, he was also an incredibly gifted general as seen with his victories against the Ottomans which led Michael Axworthy to title him the “Napoleon of Persia,” and he was also diplomatically gifted as seen by the treaty with the Russians to withdraw all of their troops from Persian territory.

##References and additional readings:

Michael Axworthy, The Sword of Persia: Nader Shah, from Tribal Warrior to Conquering Tyrant, 2006.

Erewants’i Abraham, History of the Wars: 1721-1738, tr. George A. Bournoutian, 1999.