Tā de chúyì tài chà, zài zhuānyè chúshī yǎnzhōng gēnběn bùrùliú.
His cooking skills are so poor that they don't even register in the eyes of professional chefs.
Tips
history
不入流 originally comes from imperial China's nine-grade civil service system (九品制). Officials below the ninth grade were 不入流 - too low to even be ranked. Today it means anything beneath a recognized standard.