Expected, but they must have some way of locking it down that we’re not aware of. That should tighten the seal and maybe even shut the leak at the bottom off totally.
I agree, shouldnt expect to see a dramatic difference yet. Imagine connecting two water pipes together while the water is running...many steps needed to be done now...a mile down.
there is a rubber gasket on the bottom of the cap, and then an O-ring inside the cap. Once the cap is seated, the O-ring will be compressed hydraulically to make the inner seal.
I doubt that they have done that yet. BP said it could be 12-24 hours before they will know if they have a seal and if it is working or not.