“Pretty sure this singer of “Cara Mia” is the second Jay, whose surname was Blatt.”
You are absolutely correct.
Jay Black (David Blatt) was the second ‘Jay” and is the same singer in the video posted and the 2011 video.
After the break up of the group, Jay Black (Blatt) toured as Jay and the Americans with new members. Due to debt (from gambling) his had to sell the name, Jay and the Americans which was purchased by some of the original members who are now touring with a different Jay.
Jay Black performs as Jay Black. (sorry I do not know the timeline)
The first Jay (John Traynor) left (foolishly) after their 1st hit “She Cried”.