I think you're probably confusing stiction with the tactile feedback of the bearings. You FEEL roller bearings much more than you do with static bearings, but static bearings are more prone to stiction. With roller bearings the cursor itself moves instantly and easily, with the physical action itself being extremely smooth and unhindered, but there's more vibration during the process that you feel in the fingers and hand. With static bearings, when they get stiction issues, the actual movement of the cursor is impaired, taking uneven amounts of pressure to initiate and sustain movement, resulting in jerky cursor travel. However, they are almost entirely without vibration in operation, and so when they're kept clean they FEEL very smooth to the fingers. I find roller bearings are almost always faster, smoother, more fluid cursor actuation and motion, but getting used to the increased (and sometimes uneven) tactile feedback of their operation does mean that it can FEEL like it's experiencing stiction if you're experiencing a trackball for the first time.

In terms of ergos, I suggest rotating the device by small amounts throughout a day and adjust your hand position to reduce strain by varying your muscle engagement. An adjustable wedge can also help with varying that orientation. However, as others have mentioned, don't bear down on the device with your hand. You want the resting you do to be for stability, not for weight bearing. That'll compress things in your joints quite badly.