The Team of the Week is comprised of:

The two highest scoring opening bats (either batting at 1 or 2)
The highest scoring players batting between 3-7
The best performing wicket keeper based on dismissals, then runs (who is placed at 7 but can be anywhere in the original team)
The best four bowlers

Where someone fits more that one category above, the team is selected based on:

Wicket keeper first (who could have opened the batting but does not take one of these two spots)
The best four bowlers (regardless of where they batted)
The best two opening bats (not in the selections above)
The best four middle-order players (not in the selections above)

Where two players are level the selection is currently random.