I used BJJ as an example of one of the weaknesses I've observed in MMA. A couple other weaknesses include what appears to be a complete emphasis on one-on-one confrontations against someone in your weight class, a lack of emphasis on being equally skilled as both an orthodox fighter and a southpaw, etc. Don't get me wrong: MMA's great for learning how to be dangerous in a hurry which is a huge advantage over the more classical arts. On the other hand, the one-on-one emphasis and focusing solely on learning how to fight right or left-handed are some issues I've observed at the gym I've been training at lately.