Before we can discuss policy, we have to talk about the overall problem in the Middle East.
Overall Problem: Rampant sectarian intolerance. Shi'ites don't like Sunnis, and Sunnis don't tolerate the Shi'ites. With Sadam in Iraq you had a minority Sunni population suppressing the majority Shi'ites. In Syria, you have the minority Alawite population, which is a spinoff of Shi'ite, largely suppressing the Sunni population. So for ANY of this to be resolved, the sectarian intolerance has to be addressed. That's not an easy thing to solve when eye-for-an-eye and blood-for-blood is such an ingrained mentality.
US Position: The US position recognizes the actual problem. The plan was to arm and train moderate rebels who believed in this too. They would come to power, and bam, you have people in power that actually start practicing tolerance. The problem? These individuals are very few and far between. By far the most dominant rebel groups in Syria are the ISIS-like fundamentalists. They're letting the FSA (Free Syrian Army) do most of the damage against the Syrian government, and when the Syrian government collapses, they'll swoop in and wipe out the FSA.
The end result of the US's current policy? Mass genocide of the Alawites. Further mass migration of the population. Solidification of ISIS's position, and with that escalation of war in Iraq. And because the Iraqi Army struggles battling just a smaller portion of the ISIS military, we can expect that a full strength ISIS invasion of Iraq will result in full US military intervention. Awesome!
Russian Strategy: The only thing of interest in Syria to Russia is the access it gives them to the Mediterranean. Oh yeah! That and because they want to build an Oil/NG pipeline from Iran to Iraq and through Syria to be a competitor to Russia's dominant supply of NG to Europe. If Assad gets ejected, then the pipeline gets built, and if the pipeline gets built, then Russia has competition to their NG empire.
So What Good Comes Out of Russia's Strategy?
The Russian strategy does one thing that the US strategy does not; it protects the Alawites. Putin doesn't care whether the Alawites are all slaughtered, but he does recognize that it'll happen. The Russian strategy also does one thing better than the US strategy by taking on the real threat to the Syrian regime directly, and that's ISIS.
The end result of the Russian policy? Assad will likely stay in power, a mass genocide will be prevented (after a lot more people die), ISIS will be bludgeoned by a real military on the ground for a change, and sectarian intolerance will stay the norm. Since the true issue will never be properly addressed though, ISIS-like elements will survive.
What SHOULD the world policy be? In order for the Syrian situation to truly be resolved, this requires a hugely expensive, costly, but necessary multinational coalition involving the US, Russia, Turkey, and Saudi Arabia to invade and divide up the country just like we did to Nazi Germany.
1. Assad stays in power to oversee the transitional government and/or the government becomes much more representative of the populace to begin the process of eroding the significant amount of intolerance within the region.
2. The Syrian Army stays intact. Can't make the same mistake.
3. The rebels required to lay down their arms and is completely forgiven just like the US South was.
4. Coalition militaries stick around long enough to enforce cooperation and re-assimilation of warring populaces together.
5. ISIS is wiped out. Completely.
6. Education campaigns in cooperation with tribes and mosques so that tolerance and love is practiced more regularly.
Trillions of dollars spent when all that had to be practiced was love. Awesome...