Shouldn't you add a Fallen Druid since you added graveyard?
Graveyard -> Skeleton
Skeleton + Eternity -> Random Creature
Fallen druid produces mutations, Mutations > random creatures in many games.
True. But there is that fine line between being good enough and overkill:
Random creatures (good enough) < Fallen Druid giving mutations (sometimes great, usually overkill)
- and -
Using good deck with 1 card less > adding 1 card more which may "in many games" give some extra value that may or may not be needed for winning.
All in all it really comes to players preferences & playing style. Some may like to get more splashy wins after using F.D., while others settle with bit less spectacular wins and less messing around (clicking on ~10 mutant creatures with abilities every turn). I believe both strategies will have about the same win rates though.