You have to have ground fighting and stand up to be a good fighter. All MMA guys practice BJJ even if they have a wrestling back ground. Having said that many ground fighters have no stand up and many strikers have no ground game.
Darren join a BJJ dojo for awhile. It will be an education. On an opposite spectrum when I was 25 I joined a boxing gym. Thought I could hit hard. I had a lot to learn. My first fight in the ring was against a Golden Gloves fighter. Couldn't defend myself. I missed punches. But hey I had that one hard punch. He beat me pretty bad. The next four fights in the ring I won because I learned how to fight. I stopped boxing because I wanted to remain good looking. My face was getting pretty messed up on boxing. Blocking punches with your face is a not the way to do it.

Same thing with BJJ many years later. Looked at some of the guys in the gym and thought they look like nothing. I weight train and I'm built. After saying uncle many times getting tapped out I came to a realization I had a lot to learn. I was never good at BJJ but I did learn and have a ton of respect for them. It seems the best BJJ guys come from a wrestling background. They seem they soak it up quickly.
Fights normally go from strikes to a clinch then to the ground. Guys like McGregor are really good at avoiding take downs so his superior striking can work. His ground game is weak. Other guys like Royce has a top shelf ground game but zero striking capability. Balance is the best approach.