Of course. The Russians are spending all the time and supplies on that "old stock", which also happens to be crewed by Russian soldiers who are killed during that Ukrainians "clean up".
That sounds kind of like trying to break the other guy's fist with your face.
The Russians were never that smart (in wars). Their soldiers are cannon fodder.
To be fair, it's the same deal in the U.S. Vietnam, Iraq, Afghanistan.