After testing the deck relatively thoroughly on mtgo I have some observations:
Quite a lot I have to mulligan my first hand or two because of having no plains.
A lot of people just nuke all my creatures with 1 or 2 mana removal as I play them.
getting enough plains out for emeria to actually work is near impossible.
I did swap one savannah lion for Isamaru, Hound of Konda because he is strait better (unless being legendary is that bad a thing?)
Yeah, that will happen on MTGO (they actually have some competitive Legacy decks). But compared to your meta the deck should do fine with a few more basics (mix up the count, maybe drop a Memnite).
Isamaru is easily a 3-of, but I left him off the list to keep it cheaper (they are $2 each over here).
Some Tectonic Edges will serve you well, since they can stall the opponent for another turn (important for WW).