I do not understand for the life of me why you are panicking when it's still June. Bizarre.
Let's follow this through:
What are our aims for next season in terms of league position? most would agree Top 4
What levers do we have to achieve the objective? off the top of my head the following, no doubt others can add more elements:
A) Signings that improve the team and address our weaknesses
B) tactics, superior teamwork, collective, mental strength, variety of different options to cause different problems, prioritising our resources to a single aim
Everything under B) is what the manager has complete control over but you can't just throw all of that together at the last minute, you need (C)
The quality of A) is what will determine our success, if you sign average players you can mold them into something good but not something great.
Right now, we are starting in a massive deficit compared to where we want to be, so you may think I'ma fucking loon but honestly, we need to get a move on because there is alot of work for the manager to do and the teams above us have already signed/agreements in place for better players than we have so his job only becomes more difficult.