Dear Dr. Trillwing,
By now you have no doubt deduced that you were not a finalist for our position for [xxxxx].
While it is a cliché, in this case it is a true one, that we had a very strong pool with far more fine applicants than we could possibly consider. It is also a cliché, but also true, that matching a job to a candidate is as much a matter of the needs of the program and institution as it is a matter of any absolute standard of excellence.
I sincerely hope that you remain enthusiastic about your scholarly career, and wish you every success in the future.
[Scholar trillwing admired tremendously even before receiving this excellent letter]
Now that's class, people.