#3 Late realization that they had the wrong sets of players

All the clubs usually use the winter transfer window to strengthen their weak points. Unsurprisingly, it is the bottom-placed clubs and the mid-table clubs which splurge their money. In the ISL, ATK pushed for a top 4 spot with their transfer market activity but failed to do so.
They released Moroccan Noussair El Moumani and Eli Babalj and loaned out Cavin Lobo to make space for Pritam Kotal and Edu Garcia. They even wanted to sign Sandesh Jhinghan and Miguel Palanca Hernandez but a salary cap halted their ambitions.
By the time they signed Edu Garcia and he could gel with his teammates, the season neared its end. The scenario with Pritam Kotal wasn't different either. Even with the limitations of an English coach in the Indian football, Steve Coppell could have led ATK to glory if his players performed. But, they failed to adapt to his philosophy.