In the defense industry Russian reliance on imported components is fairly low. Most of the weapon systems Russia produces would still be produced the same way with little to no difficulty in the face of western sanctions.
However the Russian Military is not what you saw in Crimea. The units used in Crimea were elite units, predominantly recon and special forces. Their equipment, discipline, and training, are far superior to that of the regular units. Also they were conducting primarily a show of force, with some use of non-lethal force against a demoralized, disorganized, and poorly trained adversary. All things considered the operation was well planned and well executed but does not reflect the state of affairs in the Russian military more broadly.