He played against Chamberlain, Walton, Moses Malone, Dawkins, Gilmore, Parish, Sampson, Olajuwon, Ewing and several others. You could argue that every one of those guys except maybe Dawkins is better than every single 5 in the NBA today, and none of today's centers could stop Dawkins either. Phil Jackson joked for years about the "fodder" teams would send out against Shaq every night during the late 90s and early 2000s. Imagine a playoff team in the 80s with freaking Scott Pollard, Greg Ostertag or Andrew Bogut starting at center, but that happened in the "modern" era of the NBA. Most of today's centers are undersized and soft and Jabbar in his prime would average 35 points and 15 rebounds in today's game, if not more.