not always. Case in point, our brand new F-35, the multirole aircraft that is supposed to replace every other western airframe.
Back in the 90's Lockheed bailed out Yakolev, and "bought" the full design plans of the new Yak-141 VTOL. That design was improved on over the years, and became the basis of our new top secret wonder weapon, the F-35b. So it would be a mistake to underestimate their potential and classify them as big mouth bull$%^##ers.
The Russians have some very capable designers, and a dedicated military, but what they do not have is the unlimited funding we have access to. As a result they focus on many low-cost, high reward aspects of military technology - electronic warfare, sniping, etc, instead of cranking out vast fleets of hardware which their small economy can not afford.