Decline of Hanifite, rise of Shafite and the birth of Zahiri

The decline of Hanifite School (Abu Hanifah) in Iraq is likely due to the rising influence from the Shafite school (Shafii) of Islamic thought.
 

Despite being anti-qiyas (Abu Hanifah approach), the Sunni Imam (as-Shafii) did make some concession in application of qiyas (analogy). Imam Shafii accepted Abu Hanifah qiyas only pertaining to orally or written transmitted sources (The Quran, Sunnah and sayings of the Prophet). 

The author also stated that antagonism against Abu Hanifah remained in the Shafite School for a long time despite themselves adopting the qiyas approach in their teaching. Author supported his view by providing statements from Fakhr al-Din al-Razi (a Shafiite) who was an outspoken critic of Abu Hanifah.

Soon enough, many of al-Shafii earlier followers turned back towards ra’y (these were known as ashab al-ra’y) i.e., Abu Thawr al-Kalbi al-Baghdadi, al-Husayn b. Ali al-Karabisi al-Baghdadi and Sirhab b. Yusuf Abu Tahir al-Tibrizi.

Another follower (Shafite), Abu al-Hasim al-Dariki rejected teaching of Abu Hanifah and Imam Shafii and would give out verdict contrary to his predecessors by relying only on hadiths.

But the most extreme Shafite (only hadiths, nothing but hadiths) was Abu Sulayman Dawud b. Ali b. Khalaf, the founder of Zahiri/Dawudi school.