I'm glad you see the light! Ferrer is the modern Borg, and though Ferrer hits harder and arguably plays with more tenacity, Borg had an edge on speed and better consistency than Ferrer. But I honestly don't see Borg beating Nadal on clay or Federer on grass.
Borg's speed was impressive, but he was by no means a phenomenal runner. Wayne Gretzky makes him look slow here. I'm not saying that Nadal, Fed, or Djokovic are much faster than Borg, but let's not get carried away.
Skip to minute 20:00 on the video to see Borg in a race.
Borg is being underrated in this thread.