"Certainly the speed you shoot from an ordinary HD to Ultra HD [changes]. We experimented in Cardiff with some of the pictures and we found that the cut rate slows down slightly. Similar to the 3D coverage, you allow more of the picture to tell the story than you would in HD. You don't need big close ups of players.
"The challenge at West Ham is that we are lower and closer to the pitch, and it takes a while for the lens to catch up with the speed of the cameraman's zoom control.
"If a goalscorer runs away you'll be seeing him from head to toe [rather then just his top half] - the definition improves dramatically so they are the shots we are working with.
"We also have an issue with the shade - it's giving the engineers extra challenges because it takes them a while to anticipate when they have to open up the iris for us.
"They have to anticipate a bit more than they would in HD. There's a certain amount of time it does take the engineers in the back of the truck to react to the change."
So what's Mills going to be working on going forward?
"We only have four cameras at the moment because that's all there is in Ultra HD at the moment!
"As more cameras become available we'd love to try putting a few more in different areas and try different things. As co-operative as West Ham are, they won't let me move cameras during the game
"If more cameras become available we'll take them somewhere and try a few different things."
With Ultra HD still a nascent technology, Mills is likely to have plenty of time to craft his art before we see a Sky Sports Ultra HD broadcast, but there's no denying that he's excited for a 4K future.