I have theory about our 'lack of major transfer movement' till now.
I think all/most of our transfer targets think/believe they can do better. Everyone is dreaming of a RM or a Barca or Juve or Chelsea or PSG etc
I am sure we have agreements in place with a few players but its just a question of execution. The last few years have been crazy with regards to transfer fees and player salaries. It still is. The ridiculousness of it all has a lot of people (players and agents) wanting to cash in and thinking 'winning the CL with Barca would be amazing'.
I think as the windows nears closure suddenly a LOT of players would be becoming available and 'wanting to play for Arsenal'