MERS' - crafted deeds of trust might legitimately have stated that MERS was to act as
the agent of the beneficiary. The agency might have been unambiguously expressed and such
expression would arguably have been ratified by the trustor, the borrower, except that, and this is a big 'except that' as discussed below, it was not the borrower who most urgently needed to expressly
appoint Mers as agent - it was the beneficiary.
 
Significantly, MERS chose not to call itself the agent of the beneficiary and the "why not" question is unavoidable. The reason appears three-fold. 1) MERS did not have a proper understanding itself of the parties to a deed of trust, 2) MERS made a conscious decision to avoid "agency" for the liability which comes with it, and 3) the deed of trust would have required the signature of MERS as
well as the beneficiary. It may also be that MERS had no intent to allege the useful 'agency' when its dot was formulated. At any rate, MERS chose the restrictive word 'nominee' instead, a mighty distinction recognized by a justice of the Massachusetts Supreme Court in recent oral arguments before the court. For its failure to correctly understand and identify the parties in a dot,  MERS asserted inappropriately-named (extra) parties in the dot and then errantly gave itself more than one identity in the instrument.  MERS' dot says MERS is both a nominee and the beneficiary itself, a legal impossibility evidencing its own misunderstanding of the parties to a deed of trust.      

If MERS had named itself as the agent of the beneficiary in the deed of trust, there would in this writer's opinion be no potentially fatal confusion about the identity of the party with the beneficial interest in the deed of trust, for MERS does not hold a beneficial interest in any deeds of trust. On first thought,  one might posit the deed of trust could recite  "ABC is the beneficiary of this deed of trust and MERS is
the agent of ABC its successors and or assigns." (The successors and or assigns is another story, as usual). However, even had an agency relationship been otherwise appropriately stated, because of the statute of frauds, it still would not pass muster.   

Only the trustor, the borrower,  signs the deed of trust.  The lack of the other signatures on the 
instrument  would vitiate any finding of agency. And this, too, in the writer's opinion is born of the unbelievably reckless crafting of the MERS' deed of trust.

The Statute of Frauds of most if not all states requires that all contracts pertaining to the sale of or interests in land, which is a description of a deed of trust, must be in writing to be enforceable.  Therefore a contract appointing an agent to make other contracts, having reference to the conveyance of interests in land such as an assignment, must be in writing under the statutes.  Significantly, such agency must be clearly expressed and may not be found impliedly. 

The statute of frauds requires that certain contracts be in writing, and that they be signed by ALL parties to be bound by the contract. In the case of the deed of trust, this would mean the trustor, the trustee, the beneficiary, and MERS. The purpose of a "statute of frauds" is, as the name suggests, to prevent injury from fraudulent conduct. The abuses these statutes were designed to prevent are quite real.

MERS is not the beneficiary of a deed of trust. Having failed the litmus test for agency, MERS may not be found to be the agent of the beneficiary nor its successors and or assigns.  What position, if any,  this leaves MERS to occupy in the deed of trust remains to be seen as courts squarely confront the matter and its attendant issues, including assignments done in its name by its members.