I stretch quite a bit but I really did not notice my flexibility improving much for years after until I started trying a new method. This method is something I learned from my BJJ professor who is the best BJJ instructor in the world according to various BJJ magazines. If you want to do a sport like BJJ for many years, you must develop healthy habits that become a part of your life that are implemented daily. This method is done by performing static stretches after a hot bath. A sauna will work as well but I prefer a hot bath. When you stay in hot water for about 20-30 minutes your tissues become very supple. You will notice your flexibility will increase instantly and you will be able to go in to stretches much deeper than you usually do. If you keep performing stretches afters hot baths for a couple weeks, you will cary over this new gained flexibility in your daily life and workouts.
One thing to make sure, not to do, is getting ahead of your self and pushing too hard during these seasons. Try to slowly increase your flexibility and do not push too hard or force anything. I usually stretch for 20 minutes after a 20 minute hot bath. Sometimes repeat this routine 2-3 times depending on how sore I am. It works wonders.
This will tremendously help your recovery and you will be a much more flexible athlete. BJJ players that have tight glutes and have trouble playing guard should definitely implement this routine. Judo athletes who want a better flexibility to execute techniques such as uchimata (wizard) should also try this as well. Thai boxers also can put this tool to good use. Athletes need to be more flexible to improve performance and prevent injury.
This is a great tip that will serve you well. Make sure to progress slowly.
Check out video below for some static stretching exercises