'Opening up' as Jake mentioned, was more a term for the grains separating when the bat is well used. It's now become a term used for when a bat starts to feel more pingy i suppose. However, any bat will generally only get better the more its played with and will feel its best just before it delaminates i feel. Maybe its the face getting better, maybe it's the handles softening a little.
In terms of pressing, the batmakers I've spoken to believe there is no such thing as 'soft pressed' or 'pro pressed', just under pressed. I see a lot of new bats coming through the workshop for repair with big indentations and cracks. Maybe because they're underpressed, or probably more because they're overdried and underpressed to achieve 'big specs'. Either way, imo neither is good for the longevity of the bat.
I've also had people saying they've knocked their bats in for 5 - 6 hours and are still seeing big indentations. Surely that's not what anyone wants! 😆