不能顧後 They Could Not Guard Both Ways
那一二百個小妖顧前不能顧後，遮左不能遮右，一個個各自逃生，敗走歸洞。這行者與八戒從陣裡往外殺來，可憐那些不識俊的妖精搪著鈀，九孔血出；挽著棒，骨肉如泥。那一二百个小妖顾前不能顾后，遮左不能遮右，一个个各自逃生，败走归洞。这行者与八戒从阵里往外杀来，可怜那些不识俊的妖精搪着钯，九孔血出；挽着棒，骨肉如泥。
逐句解 Line by line
Those hundred or two hundred little fiends, minding the front and unable to mind the back, shielding the left and unable to shield the right, each one of them fled for his life and ran beaten back to the cave.
Two limbs cut to the same measure, and the shape is the point: whichever way you turn you are open somewhere else. 顧前不能顧後 is still a live expression for being overwhelmed on every side at once. The novel does not say the copies were stronger — only that there were more of them than there were directions.
Pilgrim and Bajie came slaughtering their way out from inside the ranks. Pity those fiends who did not know a good thing when they saw it: those the rake caught bled from nine holes;
不識俊 is not knowing quality when it is in front of you — a sardonic way of saying they should have run sooner. 搪著鈀 takes 著 as zhe, warding continuously. Nine holes is the standard count of the openings of the body.
those the rod caught, flesh and bone like mud.
Seven characters. The two limbs here are strictly parallel in themselves, three characters and four on each side, but twenty-three characters of narrative run in front of the first one and none in front of this, so they are kept apart. 挽著棒 takes 著 as zhe once more.
The rout is described almost entirely through geometry. The fiends cannot cover front and back, left and right; Wukong has simply produced more attackers than they have sides.
Then the novel turns brutal for two lines. Nine holes bleeding, flesh and bone like mud — this is the same book that has spent a page on Bajie arranging pebbles at a graveside, and it does not soften the change of register at all.