Any company that stores patient information, even encrypted, is now considered a BA under the 2013 rules. Simply having persistent access to the protected information is all that matters.
The key for determining exceptions that might apply is defining the transient vs persistent nature of access. If the access to data or your level of access to the data is very rare, very brief in nature and then removed, you may not be a BA. If, however, your access to the data is always present, then you are a BA. Even if you have no need to see the data, the fact that you have it consistently available makes you a BA. The Final Rule specifically states that a data storage company is a BA even if they store the data in an encrypted format - what matters is it is always on their servers.