Your rocks need to have the capability to shield all the other ships in your fleet more easily. While the distraction technique has proven partially successful, the number of missiles that went past your rocks and into the battle fleet was unacceptable. Moving your rocks farther forward will not prevent this problem, only reduce it in the short term. I think upgrading your PD anti-missile missiles should be a priority.
Good plan in theory, but two practical problems:
1) Our Point Defense did a wonderful job of shooting down the incoming size-4 missiles. Only a few salvos got through our interlocking PD defense, and none of them scored any internal hits. It was the deluge of size-1 missiles, in salvos of 19 missiles each, coming five seconds apart, that we couldn't cope with... in fact, I even turned our PD defenses
OFF at that point, because it would just have been a waste of our PD missiles to even try and stop them.
Reality check: those enemy size-1 missiles were coming in at over 68,000 kps... 23% of light-speed. There is no possible way we could intercept them at our tech level, no matter how many PD launchers we used. That's why I simply turned them off. Ask again in a few hundred years. You cannot blame our "failure" to intercept them on a lack of adequate PD defenses... our PD defenses were fine, it was the three-hundred-year tech gap that was responsible.
2) The Rocks are Civilian ships, not Military. I cannot mount PD defenses on Civilian ships. The game doesn't allow it. We can build Military Rocks instead, but that will take a long time... it will take decades (quite literally) to expand the Military shipyards to that size, for one thing.
Any upgrade to the speed of your mine layers yet?
Not yet, no. That will take years. I have a purpose-built Bombarment Vessel designed, which moves at fleet speed (same as the rest of our Battle Fleet), but no opportunity to build any yet. Naval construction requires years... typically, three to five years if you include the time required to wait for free slipways, retool the shipyards, and build the ships.