I've had a RotoGrip Riot and a less than 2 year old DV8 Pitbull Bark crack on me while sitting on the rack, just this month.

Personally I believe its a combination of resin formulas that they use today, plus the lack of thickness to the shells in balls today.

I have never had one Zone ball crack....ever! And I still have 7 from the 90's. Nor have I ever had a Lane Master ball crack on me, and I had several of those as well.

The plastic bag idea sounds plausible however, and worth trying, so we'll see!