请帮我翻译一下和解释一下句子的结构吧！！！

这是一篇GMAT里面说美国经济模式的文章。主要是在批评的他们经济模式的不灵活，改革困难之类的

But Americans imagined a condition in which speculators, self-makers, runners are always using the new opportunities given by our land. These economic leaders (front-runners) would thus be mainly agents of change. The nonstarters were considered the ones who wanted stability, a strong referee to give them some position in the race, a regulative hand （这里主要指什么）to calm manic speculation; an authority that can call things to a halt, begin things again from 【compensatorily staggered “starting lines.”】这里什么意思？
“Reform” in America has been sterile because it can imagine nochange except through the extension of this metaphor of a race, wider inclusionof competitors, “a piece of the action,” as it were, for the disenfranchised. 这一段可以帮我全部解释一下吗？ 还有这里的句子结构是怎么样的我不太懂。 那里是主句？修饰语是哪里？里面有倒装省略的吗？

a regulative hand 是stability的同位语，即指stability

  2. 补偿性错开的起跑线

   3.“Reform”(主语） in America has been sterile [because it can imagine no change except through the extension of this metaphor of a race, wider inclusion of competitors, “a piece of the action”， as it were, for the disenfranchised][because原因状语从句].

这句话大概在说在美国的所谓改革不见成效，因为改了半天也没啥变化，除非通过以下几种方式改革。然后就说了3种方式。这3种方式就是并列的3个分句，是由except through引导的。然而这个except through又居然被省略了两次。can imagine no change就是cannot imagine change,无法想象出会有什么变化。extension of this metaphor of a race是扩大这个在比喻意义上的竞赛的规模，as it were是仿佛好像，表示前面的部分是个类比。disenfranchised是没有发言权的，被剥夺了权利的意思。