Sorry, but whoever wrote this is an idiot and has no understanding of value over replacement.
A replacement player is always a minimum salary player because even if you're the Yankees you still could start that player. If what a replacement was depended on how much your team made the value of it wouldn't be consistent at all and would thus be a worthless stat.
Kyle Howard commented on "Single Page App" Website Style Sucks!.
Slow and unresponsive, and the data does not have its own resource locator, so it is impossible to bookmark anything. When you return to the site, you have to go through all of the navigation steps again, rather than linking directly to the page with the content.
Ajax calls are useful for nagivating through content (eg. a catalog, tab blocks or tables with pagination) on the same page. That way, only the actual data needs to be reloaded and you don't need to reload the rest of your page over and over.
Another valid use case is eg. form submission. It makes more sense to use Ajax to submit a form and show the server's response than reloading the entire page.
Those are the only use cases I can think of from the top of my head where I'd actually use Ajax calls. Loading totally distinct content via Ajax throughout the same page is simply madness.
Acutally, regular form submit is cleaner than ajax submit. With regular form submit, the user's back button will take him to the page with the form filled out, if there's a problem. That problem specifically occurs on my current project. When data is eaten due to a bug, the users can't go back to the old page, because it's ajax and not a proper page.