Yes and no really. While they do have a really good match up against Chaos Dragons for the most part, they have a pretty variable match up against Inzektors and Dino-Rabbit and an absolutely terrible match up against Dark Worlds. The large amount of back row hate in this format really hurts them to, if you can't keep Necrovalley on the field, Chaos Dragons will trample you completely.gravekeepers seems to be the deck to run this format , it has an awesome match up against chaos dragons , good against inzektor / rabbit , dark world may be the only bad match up but the side should do work there .
Inzektors and Dino-Rabbit is variable just because it really depends on the opening hand. If Inzektors open with Dragonfly and Hornet, it is basically game. If they couldn't equip from the hand it would be fine, but they can, so Necrovalley will not be slowing them down. The Dino-Rabbit match up can be decent depending on how well you can keep the Evolzars off the field.
Dark Worlds are the real menace. Gates and Grapha mean that Necrovalley will basically never be up, Grapha can basically trample anything that GKs have, and by running Skill Drain (like many do) Grapha basically becomes impossible to take down. The also make one of the most powerful tools GKs have, Royal Tribute, a horrible dead draw that benefits your opponent far more than it does you.
To put it simply, Gravekeepers are good, but they still have the consistency issues they have always had, and a really heavy reliance on back row in a format that just isn't kind to back row.