BRG is a grindy sacrifice/value deck full of small creatures (Callous Inspector, Gene Pollinator, Greedy Freebooter) that Doc Ock's Tentacles and Basilisk Collar don't close out fast enough against, since the opponent has plenty of removal like Deadly Precision and Requiting Hex waiting to two-for-one you. Erode is clean, efficient removal for their early threats and bigger bodies like Mutagen Man. Shattered Acolyte adds a cheap lifelink body and insurance against The Ooze or any artifact/enchantment threats they bring in game 2. Keep the aggressive equipment plan with Leyline Axe and Thorin intact since you want to race before their grindy card advantage takes over.