A little odd why they ditched Drupal (a CMS) for Wordpress (a blogging platform).
http://erickennedy.org/Drupal-7-Reasons-to-Switch
If all you need is a few template variations, a theme, and lots of editable content, Wordpress is a good choice as a basic CMS which is user friendly. You can easily cache the results and performance is fine; it actually makes a pretty good CMS for basic sites.
Whenever Drupal is discussed, I see people comparing it to Rails, Django and other web application frameworks.
I don't get it. The CMS market is entirely different from the custom web application market. Most web sites run on some form of content management system: Day CQ5, SiteCore, Typo3, OpenText, Umbraco, ExpressionEngine, WordPress, Drupal, DotNetNuke, eZ, epiServer and so on. This is a huge market.
People who make the above comparison seem to be guys that have started web development with Drupal or Wordpress, and progressed to create ever more complex solutions over time. Then later they discover Rails. Congratulations.
I'm of the opinion, that ultimately, all CMS suck in one way or another, I hate them with a passion, but compared to most, Drupal is a shining beacon of light and reason. Seriously.
From a financial perspective, custom web applications usually do not make sense for businesses who want a complex web site. Most companies are also hesitant to shell out 200k+ on an untested, custom made piece of software developed by a small company. Compared to that, a SiteCore solution with its 60k license looks cheaper and more reliable.