Frye says, that he (a homeopathy expert) and Iris Bell recently studied homeopathic treatment of fibromyalgia.  A new analysis - comparing published studies of homeopathic drugs to matched, randomly selected studies of medical drugs - suggests that these apparent homeopathic drug effects are merely placebo effects.
homeopathic drug effects are stronger than a placebo.
The context states that homeopathic drug effects have the same impact as a placebo, so it is incorrect to say they are stronger than a placebo. The system did likely not correctly interpret that by saying 'homeopathic drug effects are merely placebo effects' it is saying that placebos and homeopathic drugs have the same impact. 
( z1 strong :ARG1 ( z2 effect :ARG0 ( z3 drug ) :mod ( z4 homeopathy ) ) :ARG2-of ( z5 have-degree :ARG1 z2 :ARG3 ( z6 more ) :ARG4 ( z7 placebo ) ) )