The case for Compton seems to be based on three points:
1. he made loads of county runs last year
2. he has made two test tons
3. he should be "given a chance"
The response is a complex one, and in some ways is, I admit, a little tough on the guy. His two test tons were made on pitches which the Kiwis admitted had been wrung of any hint of life, and were excruciating to watch even then - noone can ever take those runs away from him, but they were runs that were gifted to any batsman with solid concentration, which we always knew was his forte.
Other than that, how has he performed in 9 tests? I have to say, he has been pretty whack. He managed to get stuck in a big ball of going nowhere in India, and when finally faced with pitches with a bit of zip in them in his eighth game was quickly found out. And if Wagner, Southee and Boult are finding him out, you can bet your life that Australia's much better seam attack will do the same. So, for me, best to cull him now - especially as Root, a natural opener, looks to the Manor born.
Now, I don't actually think that that locks Bairstow on for the six slot in the Ashes. I guess a few people will see me write that and start, but I am not certain that he is getting enough game time to be ready and I might personally look to a third party for the Ashes (possibly even Adil Rashid...)
On the wider Compton point, this evidences why players will probably never again be picked on the basis of stellar county form. At 29, he has not adapted to the extra consistent pace of ball and is too far along the path to try!