Patterson was limited to just 5 games last season after he had surgery to remove an AVM on his brain. However, he could be a good rebound candidate. The surgery should have no physical impact on him going forward and next season he'll likely be in much better game shape than he was last year. So a team that picks him up now may be buying low on a solid starting DT who will only be 30 when next season begins.
He has 99 starts in a 4-3 system not all that different from what the Giants do. He knows the division... If they're looking for depth at DT, you can see how he would make a lot of sense for them.
Another visit the Giants will be having that makes quite a bit less sense is former Dolphins QB Pat White. He hasn't been in the league since the 09/10 season, but is trying to ride the wave of the read option into a comeback. Are the Giants looking to install some of those concepts into their own offense?