The New York Giants reached agreement on a three-year, $10.5-million contract with former Patriots linebacker Jonathan Casillas, my friend and colleague Adam Caplan informs me. They also have an agreement with former Cowboys wide receiver/return man Dwayne Harris, whose agent broke that news on Twitter. Harris is getting a five-year deal for $17.5 million that includes $7.1 million guaranteed, according to sources.

Both signings are expected to help the Giants significantly on special teams. Casillas is a strong performer on coverage teams. Harris excels there as well and is also among the better kick returners in the NFL. The Giants' lack of roster depth, brought on by years of unproductive drafts, forces them to patch special-teams holes in free agency, and they seem to sign a player or two every year with that purpose in mind.

But given what the Giants are paying these guys, you can expect to see them on more than just special teams. Harris didn't get to play much as a receiver in Dallas' offense, but he could get a chance to contribute on offense for the Giants, especially if Victor Cruz struggles to recover from the significant knee injury that sidelined him in Week 6 of the 2014 season. The Giants had been hoping to beef up their wide receiver group to guard against the chance that Cruz doesn't make it back. Harris helps do that, but he also offers significant value in the return game even if he doesn't have to play on offense.

Casillas is a weakside linebacker and could be the replacement for Jacquian Williams, who is off somewhere else in free agency. The Giants also have Jon Beason, Jameel McClain and Devon Kennard at linebacker, but none of them really fits in that weakside coverage linebacker spot, so there's a chance for Casillas to contribute on defense.

The Giants could move on from McClain and save $3.1 million against the cap by doing so, but I'm told they have no such plans at the moment (even with a $400,000 roster bonus due Thursday for McClain), mainly because concerns about Beason's injury history make McClain valuable as a capable Beason replacement. Having the four of them gives the Giants some depth at a position where they haven't had much depth in recent years, and allows them to deploy Kennard strategically in pass-rushing situations.

More to come, obviously.