The problem with the playing time argument is that good teams will have slots for playing time, and they will pick up the good transfers who will obviously choose playing time with a good team over that with a bad team. So now you have the left over transfers that the good teams didn't want and there you are, no difference makers.
You have to find under the radar good players, which are unicorns, who have no other options, to find difference makers. That's a steep road to climb especially if you need multiples of those.