I will never understand it personally.Young has been tried as an opener. He averages 22. He's a number 4. Maybe a number 3 if you're pushing it. He's not an opener. Swapping Latham with Young and Blundell with Latham just means you've got a worse opener and worse keeper.
If you drop Blundell, Young isn't coming in. You cannot have a part-timey keeper in Tests unless you're really desperate (as England is this Test). There is certainly no excuse at home. If you drop Blundell, you are calling up any one of Hay, Chu or Cleaver, depending on what you want. That's just reality.
Also, putting Young at the top is just a waste. Surely we've learned this lesson by now.