Two years ago on the Monday Night Raw following Summerslam the Dudley Boys made their shocking return to the WWE for the first time in about nine years. Upon their return it was sight to see, but after a while it was clear that the momentum was wearing off. Even though they pretty much returned to help get the stars of today over I feel like they could've done more had they been booked better.
See the underlying idea is that the WWE lacks depth and long term planning which makes it easier for talent end up lost in the shuffle so even when someone big returns they could easily get lost. For example, compare the Hardy Boys return to the Dudley Boys return and you'll see this concept at work. Unfortunately, when talent get lost in the shuffle it can be hard to bring them back to a position of meaning and importance, but not impossible. This is the reason that when a talent returns it is a balancing act to keep them in the conversation and to maximize the nature of the return. However, this doesn't always happen and the returning talent becomes a sudden flop rather than an important asset.