At the lower levels I found them to be very good fast trainers but now my 2nd team is at level 9 they are not really worth it.
Today I got two players I sold the free one straight away the other a DC with a quality of 57 was offered for 24 tokens.My team average quality is 67.7 & I could buy for 1 token a 64 quality 18 years Norgen any morning.So as I said not worth it