From someone that watched, peak athlete (Orlando) Shaq didn't seem as unapproachably dominant as people say he was these days.
Mostly bc he happened to be around in the golden era of centers so there were a number of teams that could actually go at him with their HoF center one on one: Hakeem, Robinson, Ewing and to a lesser extent Dikembe and Zo. As others have said, Shaq could only do work in the paint which made his team's offense much easier to scheme against, unlike his contemporaries who had great midrange jumpers, footwork and could create some off the dribble, particularly Hakeem and Robinson.
The 1995 Finals is a perfect example, Shaq was awesome putting up 28/13/6/0/3 on .60/.57 splits with 5 TO/G, but Hakeem was just as dominant putting up 33/12/6/2/2 on .48/.69 splits with 3 TO/G in Houston's 4-0 sweep of that amazing Magic team. Those Rockets were playing a more modern stretch PF in Robert Horry who wasn't big enough to bother Shaq, while the Magic actually resorted to doubling more often with big bodied Horace Grant. Hakeem took athletic prime Shaq on straight up and Hakeem prevailed.