WHEN the Giants' morning practice ended yesterday under a baking sun, the players in their blue or white jerseys plodded up the slope into the shade of the big trees where dozens of fans waited. Some stopped to sign autographs. But long after the others were in their dorm here on the Fairleigh-Dickinson campus, Herschel Walker was still signing all the pads, all the photos, all the hats, all the footballs.

"If I have time, I do it," he was saying now. "Most of them are just innocent little kids. I think about if my nieces and nephews were out there, I'd want the players to sign for them."

But the Giants didn't think Herschel Walker was worth a three-year $4.8 million contract because he signs autographs. He's here to do much of what the departed David Meggett did, if not more.

"Herschel can do so many different things," Coach Dan Reeves keeps saying. "He's a running back. But with his speed, he can catch the ball coming out of the backfield. He can line up as a wide receiver, as a slot back, even as a tight end. He also can return kickoffs."