You can imprve Natural Fitness by increasing the players Strength and Aerobic training, then allocating two or three Fitness coaches to make them have better collective fitness.
You cannot improve on Consistency I don't think. It's just being careful with the way you praise them and not make them over-confident because then they will just walk into a match and, straight off the bat, think they'll perform well and the team will win. Look at their personality, and work on how to praise and criticise them.
As for Flair, increase their Ball Control workload, and they should get better.