This is a theory about nose bleeding. Maybe during time travel, you start bleeding as you get closer to a time where you existed in the same time/space. So Sawyer and others started bleeding when they kept getting closer to 1977. You only die because of bleeding if you actually lived what happened but you don't die if it actually happened (PEOPLE DISAGREE WITH WHATEVER HAPPENED, HAPPENED) and you just didn't live it yet. Example Saywer, Juliet and Miles didn't die but Charlotte did. This let me say that maybe Miles was on the Island for some time but never was there in 1977 because he would have died (According to this theory). This can explain a little why Sawyer said that Daniel Faraday is not on the island anymore. I believe he left the Island, or died. (Left the Island it is, I think). If you remember he was th only that didn't bleed. So, he might have disagreed with Saywer and left on the submarine. It was sometime where Pierre Chang was there.
If Miles was on the Island, I'd suggest that he was sent to real earth before 1974 by his dad, Pierre Chang I guess. It doesn't really work out well because Chang is a Chinese/Korean surname, but Miles said he was Tahitian (Not Sure). It could have been forged though.