Dave Merritt has said that Terrell Thomas is the guy who will fill the role that Deon Grant did last year in those sets.

from inside football.com

here’s been some speculation that Thomas, a bigger cornerback at
6-foot, 199 pounds, could play some safety — both because Deon Grant,
who played a big role in the Giants’ three-safety packages last year,
was not re-signed, and because fellow CB Aaron Ross has stated that he
does not want to line up at safety any more.
Thomas, who co-captain DE Justin Tuck referred to earlier this week
as a future Pro Bowler, is intent on stepping up in that third safety
role if needed.

“It’s not hard at all,” Thomas said of moving between cornerback and
safety. “I’ve played the nickel spot before, my rookie year and my
second year. We were a little bit low in depth last year, but with the
addition of Prince, Ross; Cary [Harris] being a second year on the
field, I think we’ll be able to transition.”

Looks like Terrell Thomas will play the third safety in our 3 safety sets, I think that will be a good fit for him and give him the opportunities to make plays

Aaron Ross already said he wont play safety this year.

Now for this to work we need Prince to get his ass into camp!

^ I agree uzi. I can't wait for Prince to sign and get in there.

I can't wait for Prince to get here either, he needs to go a lot of work.

Merritt has mentioned that he will likely be limited to playing outside (ie CB) as he won't be able to pick up all the reads needed at safety as well as adjust to the NFL.