The removal of sliders is not bad, neither is this new system. But it needs serious improvements:
a) Not being able to see the default player instructions is something completly out of common sense. No need for tweaking everything, simply seeing and knowing the default player instructions and how they change when we select team instructions and roles;
b) Some player instruction could be a simple on / off button, similar to the instructions in fm13 "move into channels"
c) Football is not an exact science, ruler and square, or logic: SI, through this new system, is giving us a ruler and square, something like "Here, take this, you have this roles, the logic says this roles are supposed to do this and that". So, it serious lacks some customizing not according to the SI logic, but according to our logic as managers;
d) If you are going to change the system, change it well: it's amazing how after 20 years or so of FM there are still missing basic tactical options, since you can either go for a zonal pressing (where player A presses opponent B) or man marking. Pressing the opponent with the ball, which would allow our team to have 2 or 3 players pressing simply doesn't exist. Also, it seems moral and composure are not important to SI since there is still no possibility of telling a player during a match to calm down, run more, try harder, you are doing great, keep on going and things like this.
So, I believe there's a lot more than just sliders or no sliders.