You can say what you want about Koeman, but I was noticing that they have more stats on the EPL site these days and being a complete stats nerd, tool a look at Everton's over the years to see if I could see a change in style from Moyes to Martinez to this year (most of the stats only start in 06/07). The one that stood out for me the most was "Errors leading to Goals"
07/08 - 4
08/09 - 4
09/10 - 5
10/11 - 6
11/12 - 5
12/13 - 7
13/14 - 6
14/15 - 15
15/16 - 10
16/17 - 2 (on pace for 3)
As reference over that period Man United have averaged 4 per year (min 2, max 6) while Arsenal have averaged 8 per year (min 5, max 14). RK's done something right.