Before the war began in 2011 the Syrian forces had 450,000 personnel, although 77 percent of them were short term conscripts. When the Russians showed up Syria was depending mainly on Iranian mercenaries for combat troops. About 70 percent of the Syrian military manpower had disappeared (dead, badly wounded, deserted or refused to extend their conscript service). The Russians emphasized rebuilding the technical services first, especially air power, artillery and logistics. Currently, the Syrian armed forces have about 100,000 personnel, few of them conscripts.
I'd add tanks to the list of "technical" services. These services aren't the casualty intensive elements of an army. The Syrians on Assad's side have had enough of that.
Syrian conscripts now go to militias that defend their home areas and aren't required to advance against enemy-held territory.
Ever since Syrians stopped being willing to die for Assad, Iran has provided the infantry cannon fodder via Hezbollah and a Shia foreign legion imported to fight and die. But lack of money because of the sanctions on Iran are harming that capability. Both sources of shock troops for Assad are thus much reduced.
As I noted a while ago, the Syria army evolved into something that looks more like an advise and assist force. Combined with a willingness to kill (and imprison and torture, of course) as many civilians as you need to, this has worked to regain control of most of western Syria.
Contrast this approach to warfare and building a military with the American policy of avoiding killing civilians combined with putting allied foot soldiers into battle first while we provide the technical specialists and only later train the allies to take care of the technical services.
While that approach has worked in Iraq (which had a tradition of having technical specialists) we are having problems in Afghanistan as the air force saga demonstrates.
And to be clear, I'm not suggesting by that warfighting contrast that we should adopt the "kill them all and let Allah sort them out" approach to civil war that Assad and Putin bring to the table. Although to be fair, as a minority government, terror might have been the only way for Assad to win with such a poor demographic hand going in to the fight.
Idlib in the northwest remains under Turkish-backed jihadi control and much of the northeast is under Kurdish control backed by the American coalition that helped them defeat ISIL.
Assad is now in a slow offensive in Idlib. And I assume at some point Assad and the Kurds will cut a deal over Kurdish autonomy within Syria.
