Recently there have been conflicting signs from Russia re: Syria - (like this one - Syrian oppositions just visited Moscow but came out saying they found ‘Russia’s position hasn’t changed at all’.)
This CNN piece sort of lists up ‘whys’.
[Tom] Graham, who served as senior director for Russia on the National Security Council staff from 2004-2007, said there are questions within the Russian elite as to whether al-Assad is viable as a leader over the long term. “They’re prepared to see him go, but the method and timing is important. They’re really like to see this as part of an internal process as opposed to something imposed from the outside.”