Is this a symptom of worn out torsion bars?

My son Aaron has been driving the Dart Sport we rebuilt for less than two years. While we were installing all new suspension components under his Duster this weekend, we took a look under the Dart for a reference on something and noticed the rubber bump block under the driver's side lower control arm is split and falling apart. The frame is almost sitting on the torsion bar adjuster (has actually scraped some paint off).

We used a new bump block when we built the car, and already had to replace it once about a year ago. This is the second new one in less than two years, but only on the left side. Is this indicative of worn out torsion bars not providing enough spring action to maintain lift under a load, such as bumps and dips. The street we live on has a concrete valley gutter at the intersection. When turning left into our street, the car will naturally dip down with more force on the left side. It's not like Aaron does a power slide into our street, he tends to take the dip fairly cautiously.

What else, other than low quality parts, would contribute to the frequently failing bump blocks. Would larger torsion bars prevent this from occurring?

Thanks for any insight,
Jerry