Well, with the introduction of significant and precision air support of Assad's ground forces...of course the balance of power now favors Assad.
The US could have used its air forces to do the same...realizing that Assad was a far better for choice for the people of Syria, despite whatever differences we have with him, than ISIS ever would be.
Instead the current US administration chose to try and defeat ISIS with air power alone, and a misbegotten, doomed to fail, effort to use other counter Assad forces as the ground component.
But the problem was, all along...and many, many people pointed this out, that::
1) There were not nearly enough of them, and
2) They were difficult, if not impossible to properly vet.
Therefore the US was left with air power alone...and though that has hurt certain aspects of ISIS, it is not able to defeat them and retake ground from the,
The Russians are seizing the opportunity to do just that.