You are already doing the biggest thing right and may not know it: cold dough from the fridge cuts far better than room temperature dough. If you ever score at room temperature and wonder why it is worse, that is why.
A few things that make the cut cleaner still:
Score the moment it comes out of the fridge, not after it has sat on the counter while the oven finishes heating. Ten minutes of warming makes a real difference to how the surface behaves.
A dusted surface cuts more cleanly than a bare wet one. A light dusting of flour before scoring, brushed off after if you do not want it visible.
Do not saw. One stroke. If you go back over a cut it drags and closes, and that is often what turns a good score into a ragged one.
Wet the blade if it is still sticking — a quick dip in water between loaves.
On steam, since it is connected to your result: without enough steam the crust sets too early, and a set crust cannot open however well you scored it. That produces exactly the boulder shape. If you are not baking covered, or in a Dutch oven, that is worth checking before you spend more weeks on angles — plenty of no-ear problems are steam problems wearing a scoring costume.