He means what gyms help each art transition to MMA the best. Try looking at it that way. Like how kickboxers admit that MMA striking is different. What gym would help a kickboxer the best in MMA?The best wrestlers come from DI programs, the best strikers from kickboxing gyms and the best BJJ guys come from BJJ gyms. Most of the top MMA gyms just take guys with serious backgrounds and fill out their holes.