The player poaching between the San Francisco 49ers and Seattle Seahawks has been a well-documented part of the most heated current rivalry in the NFL.But if the 49ers land Seattle free-agent cornerback Walter Thurmond it would change the landscape. Thurmond is set to visit with the 49ers. If the 49ers sign Thurmond, he'd be -- by far -- the best player either has landed from the other during this recent rivalry.In the past both teams have signed the others' former players, claimed them off waivers or signed them off the practice squad.