This is how Brian Cashman operates. Back in the days of George Steinbrenner, a third setback to Gardner would have sent The Boss into a frenzy and the Yankees would have had a new outfielder within 48 hours. The problem was that because they were so aggressive they would usually overpay. Not these days.
Instead Cashman will be incredibly busy over the next two weeks and will seek out the best possible option for the Yankees. To Cashman, it is a better option to do nothing than to make a trade just for the sake of trading in the typical Steinbrenner fashion. As a result, the Yankees get ripped off much less often in trades these days. It’s part of what makes Cashman a good GM.
If the Yankees do make a trade, it has been out there that they prefer somebody more like Gardner who can steal bases and play defense. The biggest names attached to them through rumors so far has been Justin Upton and Shane Victorino. Here is a link to BBD’s latest Yankees rumors.