Riggleman told Ladson that he was still going to split save opportunities bewteen Storen and Burnett. The reasoning being if there are 2 strong lefties coming up in the 9th, it's silly to bring in the righty just because HE'S THE CLOSER. I think this is great. Not only is Riggleman trying to get the best match-up possible in the 9th, but it also frees him up to potentially use Burnett and Storen earlier in the game when the Nats need important outs.
Now his actual use of these two seems a lot more like "Burnett was the closer. Storen is the closer now. Burnett could close again if Storen struggles" but hey, at least the right idea is in his head.
I know there is a lot of disagreement on the topic of whether you need "roles" in the bullpen. The modern bullpen is expanding things out past just the closer set to having 7th and 8th inning "guys". Sure there have always been set-up men but it's getting more and more rigid as time goes on when and in what type of games guys can appear. Managers love this because it frees them from blame. If you bring in your 7th inning guy in the 7th inning and he blows it, it's not his fault. What was he going to do? Not bring the 7th inning guy in the 7th? He's the 7th inning guy! Players love it because, like everyone, we prefer to know when and where we are going to work.
But the truth is it doesn't matter that they love it, it's a silly and non-optimal way of using a bullpen. A pitcher's job is to get outs and he should be able to do it whenever he is brought in. That being the case, you should use your best relievers in the most important spots, not save them for potentially even more important spots that may never come. Riggs' platoon closer situation would still saddle one talented reliever with many potentially less important 9th inning shut downs, but at least that pitcher can change so the other one might be used when he's really needed, not just when convention says he should pitch.