Pardon the somewhat juvenile headline, but Putin's goal, his dream of a Russia "restored" to Soviet era glory, is way too big for his military resources. His army organization is thoroughly corrupt and barely works at all, and his huge spending on advanced weapons has resulted only in a small number of tanks, missiles and fighter jets with modern capabilites. He is fighting with equipment that is outdated, badly maintained, built significantly below specification and plagued with teething problems, or even nonexistent.
As an extra bonus, Ukraine released a video today that shows a Russian T-90M, the most modern tank in their arsenal, being blown to pieces in the signature "hats off" fashion (explosive separation of the turret from the body) by an armor piercing projectile from a Swedish "Carl Gustaf" grenade launcher. This is a low cost, hand-held weapon that costs a few thousand Euros. A T-90M is orders of magnitude more expensive, and having it taken out by such a low cost weapon is a huge failure for Russia, much like the sinking of the missile cruiser Moskva.
Russia is clearly not playing with a full deck in this war.