This was the most effective point Anna Politkovskaya made when she was writing about Putin's war in Chechnya. The Russian army was a disaster at that time, riven with alcoholism, disaffection and incompetence. Putin had to finish off the job by bombing the place into rubble. Obviously, that was a long time ago, but nobody really knows if it is any better now because all of the interventions Putin has made recently (i.e. Georgia, Syria, Eastern Ukraine, Crimea) have been achieved with strategic bombing, special forces, proxy militias and mercenaries. This is their first major military campaign since Chechnya. Lest we forget, Putin's Russia was the first classic on this subject and Politkovskaya was murdered for it.
The latest classic on this subject, Catherine Belton's Putin's People, makes a key point: the Orange Revolution was an existential crisis for Putin, he felt responsible for "losing" Ukraine and tried to resign over it. When he came back after this event, he was (European leaders are now admitting) a different animal. Almost everything he did after that worked very effectively: the strategy of limited incursions and the recognition of breakaway provinces; backing Assad and reasserting Russian influence in the Middle East; putting money into foreign propaganda services, like RT, as weapons of subversion; the troll farms and co-option of foreign journalists and politicians; etc. He exposed the feeble limits of power and will in the U.S, Europe and NATO and exacerbated and exploited political and cultural divisions in the West. He could have kept the West off-balance indefinitely by applying pressure on the edges of Ukraine; his tried and tested strategy would have continued (I think) to have paid dividends, stressing and ultimately cracking our alliances.
It's hard to comprehend what he has done or why he has done it. He has thrown away all of his gains in one day. He has set fire to everything he had carefully built since 2004. It's like he lost patience with his own strategy. I have a really strong instinct that it will destroy him and that full invasion is a fatal error. I don't think he will (politically) survive this war. There will be regime change in the Kremlin before Russian troops leave Ukraine.