I've never used the RockerZ, so I don't know if they could cause that problem. But I know that if guards get dirty on the inside, they can dull blades. Keep them clean. Also, they should fit tight - any motion as you walk would wear the blades.
And of course don't store the blades in hard guards. They will hold water, so the blades rust and corrode. Hard guards should only be used for a few minutes at a time, when walking to and from the ice. Same for keeping them in a non-breathable skate bag. Blades should be stored in soakers, or uncovered, away from possible sources of abrasion.
Maybe you keep your skates outside (e.g., in a car or shed), and the humidity has changed with the weather? If you must keep them outside, oil the blades after use. In principle that helps even if they are stored indoors.
My experience with the older model of Matrix is that they were waterproof enough that rust was not a big issue - I don't oil them the way I used to have to oil my MK and Wilson blades.
Or maybe the ice is harder now, in the Winter?
Or maybe you are now a much better skater, are going faster or doing fancier things, and are noticing skids better? That is the most appealing explanation, so it must be true.
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Perhaps their quality control has gone down. isn't perfect - and your new blades might not be as hard as your old ones. A little after MK and Wilson merged into one factory, they had that problem, and about a year's worth of blades were much softer. Maybe Jackson has changed manufacturers? But I'm inclined to think other explanations are more likely, unless other people have the same experience.
P.S. If you genuinely suspect the RockerZ, line the place the blade touches with cloth athletic tape. That will cushion things a bit. If you change the tape reasonably often, that will help the contact area stay clean.