I expect the delay is Archer agreeing terms with Villa in respect to whether Villa exercises the buyback option. With a buyback clause, Archer has no choice but to join Villa. His agent will be negotiating salary in the event of different scenarios e..g. Archer scores 4 goals and is crap for Blades and gets relegated then a salary of 20k a week. But if Archer scores 15 goals, gets an England call up, and keeps Blades in the PL and Villa exercise their option to purchase him then a salary of 100k a week. These negotiations took over a week between Ramsey's agent and Villa after Burnley had announced they had agreed a deal with Villa.