WASHINGTON — There are these little things that are starting to come together for the Pistons in recent weeks. It’s not that the Pistons are becoming world-beaters or that they’ll be streaking toward a late playoff run. Not even close. It’s more that there are fewer things going wrong, and the litany of mistakes that they were making previously are decreasing. The result has been three wins in the last four games, including good wins over the Boston Celtics, Cleveland Cavaliers and Sunday against the Charlotte Hornets in overtime. The improved production includes veterans such as Jerami Grant …