Most of current good teams are selecting based on form. After just one bad series, India dropped Rahane, Aus dropped Handscomb, SA dropped De Kock etc despite great performances before their bad form kicked in. And in all cases, newcomers have performed despite criticisms selectors faced initially. One thing is clear, international cricket is not the venue to work your way out of a bad form, you should be in form already and hit the ground running. However Eng keep persisting with Cook despite repeated failures against top sides in last 5 years. Even England ODI side was able to turn tide few years ago after making bold decisions and getting rid of "reputation" players who haven't performed. Unless England dare to drop Cook (and let him work his way back into team based on performance just like everybody else), they won't improve. You can't win games against difficult oppositions having an opener who is a sitting duck to any form of good bowling. To add to it, the way Cook looks at the crease is so tentative and nervous-like, it doesn't help the other batsmen mentally either.