I was hired on with a different bank and it merged with Western Alliance Bank. Hiring at the time was very easy with a simple phone interview with HR just asking a few questions to be able to setup a time for you to interview with the manager. Once the manager interviews you, the HR gets back to you quickly and was hired on. Once hired, they did a background check and credit check.
Now with Western Alliance I heard the process is different now, so I can't comment on the new hiring and interview practices.