Russia’s Air Force is largely non functional. It’s not capable of bringing it all to the front due to a mix of parts, maintenance, and pilot shortages. The latest phase of the war has seen them trying to use their copters (which are effective) but they’re dropping pretty fast.

It’s true that surface to air missiles are very good these days. But that’s not very useful against long range missiles precision weapons. Which Russia largely does not have. See their recent use of an iskander ballistic missile to take out a company of infantry under a bridge out of desperation and lack of alternatives.