Whistling Straits mimicks a links course for the reasons vale mentioned and they did use a fescue type grass for the fairways, which is another characteristic of a links course. However, for the approaches they used bentgrass, which may not allow the ball to roll up like a fescue. Think along the lines of bentgrass as velcro compared to fescue. Links style courses also have a different type of bunker (called 'Scotish bunkers), using sod faces that allow for very deep bunkers. The sand in links courses are also, for lack of a better term, looser or more sugarary in texture which tends to a golfer to face more fried egg lies. I don't think WS used these features in their bunker construction - the sand around the greens will probably play very much like the pros see from week to week.