I don't remember Rodman shutting down Shaq... but that was a long time ago so maybe I don't remember things that clearly. Still, "shutting down" is a pretty strong term. Rodman did a decent to sometimes very good job on Shaq considering the size difference, but saying he shut him down seems like quite an exaggeration. Still, what made Rodman so great was his relentlessness. He was pesky, he was physical, but he didn't let up, not for one play. But what also helped him against Shaq were a couple of things. In the mid to late 90s, Shaq was huge but not the 350+ pound monster he would later become. So as much as there was a size difference, it wasn't nearly the size mismatch it would have been later on. Secondly, Shaq still relied mostly on his sheer size, strength, and athleticism. Shaq got better with his touch around the rim later with the Lakers, but not as much when he was still in Orlando. That was to Rodman's advantage. Still, I don't recall Rodman shutting Shaq down. Slowing him down better than most? Sure. Maybe making a few really key stops. Ok. But shutting him down? I guess I'd have to see those games again to believe it.
Against Pau Gasol, Rodman in his prime would do a great job. But the difference here is that Gasol has size and skill. We can talk about the rules changes as well and that would benefit Gasol, just like we saw Grant Hill get in foul trouble with limited bodying up on Kobe last night. Rodman was the type of defender that put his entire body on you, chest to chest. He would get a lot more foul calls in today's league, if we're playing by the rules now. And, then there's the fact that Gasol has perimeter skills, dribbling, shooting midrange, left and right hook shots in addition to a huge length advantage. Rodman was 6'7, maybe 6'8, but that's pushing it and probably in his bulkier days about 220 lbs. He played mostly around 210 in Detroit and probably in San Antonio as well.
Even if it was proven or conceded that Rodman shut down Shaq, that doesn't necessarily mean he would shut down Gasol. Gasol's skill set would cause problems for a defender who was super aggressive, physical, and tried to use strength and leverage against a player. That works better against a player like Shaq, not as well against a player like Pau, even though Pau plays like a pussy a lot of the time.
I agree with the sentiment that the 90s NBA were relatively weaker than they were in the 80s and even in many of the years in the 2000s. But, those Bulls teams were still unbelievable. Despite having a wide gap in talent from the top two players versus the rest of the team, what made them so good was those less talented players were so good at knowing their roles and playing those roles well. Shooters shot well. Defenders defended well. The role players didn't try to do more than their own individual limitations allowed them to do. That's how a team with a player like Jordan became so great.
I think a 7 game series between those 90s Jordan teams and the current version of the Lakers would be a lot closer than some think, because of the disparity in talent of the front courts. Those Bulls teams did not have great front courts and they didn't face really good front courts in the playoffs. Faced some great individual front court players like Ewing and Shaq and Karl Malone and Barkley, but not really great front courts. The Lakers would pose some problems with size and skill up front. But Jordan would still give Kobe a new asshole, and those Bulls would ultimately prevail. Closer than some would say, probably a pretty well contested 6 game series.