Even bone is soft compared to steel rods machined to sub- micron tolerances for a physics experiment. Biology experiments are also soft in that they sometimes to work under a wide range of conditions, and the important parameters can be hard to nail down. And then sometimes experiments stop working, even though you are following the protocol as carefully as possible and you are convinced you have thought of everything. No one knows why, but clearly you haven't thought of everything. Some variable is not under control.
Biology is also part art.
We speak of people's hands. She has good hands, all her stuff works. This procedure never works in my hands. I can't imagine any self-respecting physicist talking that way. In physics, the lines are sharp and clear like the metal casing of a particle accelerator.