It was not the blocks that failed - those same blocks are used all over the world at many high level meets. The problem was the track at Ichan.
The track is used for many many very large meets all through the spring and summer and even into the fall. It is also used for practice by many teams in NYC. If you look the area around the starting lines has been cut out and replaced and even with that the surface is all chewed up.
The blocks were fine, the spikes to hold the blocks were fine. It certain lanes starting area the track surface is crumpling so the blocks slipped. It was the track surface not the blocks that were the problem
If it was the blocks there would have been many more issues this past weekend.