I'm going to cover your current three top fighters because it takes a while to look through their fights and everything.
Bret The Grinder
5/10
Bret has shown solid KO power and good heart. The main reason I scored him at a 5 is his mediocre chin and the fact that at 25 years old his highest primary skill is superb. I believe he could hold a title or two at a middling org, but his age will make it hard to take his skills to a truly competitive level, and his chin will make him particularly difficult to depend on. He may not ever be a top level killer, but he is a fun fighter to watch.
Rafael Cruz
7/10
I love a BJJ guy that rolls KO power. Even though Cruz is already 25 he has shown good power and has a brown belt to back him up on the ground. I think it is interesting that you tend to set him to strike so much in his fights, given his low level of ability, but he has a solid record and if he focuses hard on training up his striking he could do very well in the future.
Tremaine Van
7/10
Fighters with real KO power in the 155 weight class or below are pretty rare. I think striking is your strength as a manager and with that in mind Van has good potential. He is 26 and so he will start training more slowly with each passing year, but if striking is heavily focused on he stands to do pretty well.
Overall I’m impressed by your ability to utilize your fighter’s power effectively even if they don’t have the skill level to back it up. I would encourage you to try out some 18 year olds because most top guys are nearly maxed out in a lot of skills shortly after the mid 20’s mark.