MLS is a growing sports league in the U.S., but the athletes are poorly paid. It will not become a real "major" league until their pay becomes competitive with the others.
Average major league player yearly salary in USA
baseball $3.8 million
basketball $5.1 million
football $1.9 million
hockey $2.7 million
soccer $226 thousand
Notes:
1) Median salaries are lower than the average in every sport.
2) The average player salary in the English Premiere League is $3.5 million (2.3 million pounds)
The better MLS players will eventually go to Europe to play soccer for higher salaries.
MLS is major in name only.