Tennis ball and splotchy grass tells me you have a dog. With that small of an area it is going to be a constant battle between the dog killing the grass with his pee (Too much nitrogen).

I would start by overseeding the area and keeping any pee diluted until you get your grass back. You'll want to keep up with a chemical alternative to neutralize the nitrogen buildup unless you want to just follow the dog out and water down is spots.

Honestly if you're not opposed you can look at faux grass alternatives which will be more up front, but will not be such a maintenance headache out into the future. Add some planter boxes and it looks nice all year long.