Giunta has been coaching in the NFL for a long time but took last season off after being fired by the Giants at the end of the 2014 season. Here's a quick history lesson on Giunta, per Florio:
Giunta served as defensive backs coach of the Giants from 2006 through 2014. He was fired by former head coach Tom Coughlin last January.
The Saints have not officially confirmed this hiring yet. Perhaps we will learn more tomorrow.
The vague position of senior defensive assistant was Dennis Allen's title when he was hired last year, before taking over as defensive coordinator when Rob Ryan was fired midway through the season. Allen is still listed on the team website as the senior defensive assistant, so perhaps the hiring of Giunta means Allen will officially be named the team's defensive coordinator. Giunta might also be the next defensive-coordinator-in-waiting should things go poorly in 2016, just like Allen was to Ryan.