This article notes that Hezbollah and the Shia Foreign Legion that Iran has organized is a key element to spearhead Assad's efforts to defeat the rebels. This is surely important. And I've noted this role before.
But don't neglect the description of the state of Assad's ground forces:
Thousands of Iran-supported Shiite fighters are playing a crucial support role for the embattled Syrian regime, helping claw back rebel-held territory, defend regime strongholds, and ease the burden on the exhausted Syrian Army.
"Thousands" aren't enough to carry the burden without the far more numerous army, secret police, and loyalist militias. But as long as the Syrian forces are at least minimally capable, the thousands can spearhead offensive efforts and stiffen defenders.
The need to stiffen the Syrian forces is clear:
Crucially, the presence of Shiite militias – especially Hezbollah with its proven combat record against Israel – has served as a morale boost to Syria's weary regular forces. According to diplomatic sources in Beirut and Damascus, some units within the 4th Armored Division, an elite unit in the Syrian Army, have come close to mutiny due to the high casualty rate among their ranks. The deployment of Hezbollah’s battle-hardened fighters has eased some of the pressure on regular forces.
“In the first nine months of the revolution, the Syrian army was losing dozens every week,” says Ali, the Hezbollah fighter. “After that, the special forces, our people, stepped in and trained them and that has reduced the casualties.”
I've noted that the regular army is bleeding out in the fight. And while the other assets may be reducing regular army casualties, those other assets are taking heavy casualties, too. If the regulars are shaky now, the other assets--even the jihadis if they suffer enough casualties (remember, the Iranians broke in the Iran-Iraq War despite their supposed higher acceptance of losses due to their fanaticism).
And this is an interesting note from the article:
Hezbollah is a task force that can be deployed at will. It’s a new, capable force backed by air power and artillery,” says a European ambassador in Beirut. “Although Hezbollah is a small force, it allows the regime to concentrate forces in one area which it can’t do with regular forces. The way they are supporting the regime is strategic even though it is a small force.”
If true, this implies that Assad's forces are strategically immobile, too busy or perhaps not confident enough to be moved from their locations. If Hezbollah is the mobile strike force, Assad's Syrian forces must be tied to wherever they are. Which means that success in one area can't be exploited by moving victorious forces elsewhere. I thought I'd read months ago of Syrian redeployments to the Aleppo front, but since the government has not been able to push back rebels there, perhaps that redeployment was minimal.
So yeah, new forces able to absorb casualties are taking some of the strain off the regular army, but eventually those new forces taking the lead will endure enough casualties to make them just as shaky as the army is now (and if Hezbollah gets shaky, they'll return to Lebanon rather than break their ground forces and make them too shaky to resist a direct Israeli strike or to fight a new civil war in Lebanon if non-Hezbollah forces decide to deal with Hezbollah while Syria is busy). Assad hopes the Kerry-Lavrov deal will be the new force that saves the Assad regime before that happens.
Will we be foolish enough to cooperate? Is the Obama administration Assad's last reserve?