Pele came to the US to a fledgling league. A new soccer city. A more niave fan base. We got something that baseball could not give us anymore. A romantic legendary hero in the likes of Mickey Mantle and Ted Williams. Man above men. The TV coverage most of us saw was Jim McKay and Wide World of Sports 3 minutes of video once a month.
Beckham will come to a MLS that is almost a teenager and endured the Adu frenzy. His role in LA may be very close to how Gretzky came to LA.
The bigger comparison is the Giorgio Chinaglia/Landon Donovan interplay.