The majority of PS2 games run in interlace (480i/576i). For interlace sources you can have nice picture quality or low input lag, but not both. A little wobble/shimmer or flicker is a side effect of the lag-free deinterlacing the OSSC does. If input lag is not a concern, use pass through mode and let your display handle the deinterlacing. Deinterlacers in TVs obviously prioritise picture quality over input lag.