YPG took those areas with russian airsupport. Tal Rifaat and the airbase nearby. It did it for a reason. Creating a buffer zone between rebels and the regime in that area. Its still very signiciant cause if rebels take it, they will have 3 ways to break the siege. From the north, west, and south. No good for the russian backed regime.
¨What many dont undestand is that Syria is zero-sum game for almost all actors.
by the way, Sultan Murad and Idlib Army - both participitans of Euprhat Shield just spent a day raining shells and barrages of brand new GRAD rocket on regime held areas of Aleppo. Mostly South.