Courtesy of i newspaper, Steve Smith's test average against left arm spinners = 34, his average against all other types of bowling = over 74, so, for that reason alone, Leach should be selected for the next test.
Reminder - the First Test in the iconic 2005 Ashes series was won by Australia on day four. It was the last time I considered going to see a Test, because I was gifted a free ticket for day four, but as England had lost five wickets at the end of day three, rain was forecast and I had to make a near 600 mile round trip I didn't bother. I seem to remember England getting a worse press that day than now, incidentally.
The Edgbaston test was the first to be held that will count against the World Test Championship that will come to a conclusion in June 2021 with a final at Lord's.