Actually the Mafia dominance in heroin started to slip in the late sixties and early seventies, not the eighties. They were still big players-just not the only game in town.
I gotta disagree that Matthews and Lucas were midlevel. Barnes was; they weren't. They supplied many other black and Hispanic syndicates. This is discussed in great detail in "Gangsters of Harlem", "Easy Money", and "Black Brothers Inc."
Even today although the Mexicans are the predominant suppliers there are still plenty of other people who import and deal independently of them. The Nigerians are huge in Chicago and New York. The Cubans have their own thing going on, as do the Colombians. It's quite a melange out there.
Before the fall of the Pizza Connection, the trans-Atlantic operation between the Sicilian and American Mafias was estimated to be responsible for 80% of the heroin to New York, as well as the U.S. in general. That was down from 95% in the 1950's but the Mafia still dominated the trade. From the mid-1980's to the mid-1990's, the Chinese controlled the heroin trade. But then the Colombians started refining their own high grade heroin, and later the Mexicans as well, and they eventually replaced the Chinese.
Unless you are the group actually bringing the drugs into the country (i.e. the top of the drug chain) you are somewhere at the mid-level, which Barnes and Matthews were. They got their supply from somebody else so they weren't technically at the top. Once again, whether Lucas had his own direct connection is debatable.
Read the 2008 DEA Threat Assessment (link below). Mexican groups are now the dominant suppliers, controlling most of the drug trade at the smuggling and upper wholesale level, in every area of the U.S. except for the Northeast and South Florida. In those two areas, Colombians are still the main suppliers.
http://www.usdoj.gov/dea/concern/18862/index.htm
