Robertson was only the Yankees' closer for a week after Mo Rivera went down for the season. He was 1-for-2 in save opportunities, which tells you little to nothing if he can do the job or not. In my opinion, because of how good Robertson is, he could be an excellent closer.
However, he did seem very aware of the lack of a safety net in the ninth compared to the eighth. Would he have overcome this trepidation? There is a good chance he would have. To paraphrase Reggie, bet on talent.
Still, Soriano is now 6-for-6 in save opportunities and he has another two weeks to show he deserves the job. He is not overwhelmed by the opportunity. Instead he embraces the chance. By the time Robertson comes back -- if he even comes back in mid-June -- I think he will return to the eighth inning role. In my opinion, Soriano is going to be the Yankees' closer the rest of the year.