You most likely have Common Burmuda coming in. Its very invasive during a hot dry summer. Your best bet is to hit the field with GLY in early spring before it comes out and then go after it with lots of nitrogen. The only downfall will be if there is any cool weather the field will not recover from harsh play as fast but you can overseed with Rye then.
Knowledge is knowing a tomato is a fruit, wisdom is not using it in a fruit salad.