What happened in the early '90s was that umps started getting complaints from batters over the high strike so they essentially made a compromise and said, 'OK, we'll stop calling that but to compensate we're going to widen the zone and give the pitchers additional room on either side'. Different umps applied that to differing degrees but, in general, the zone started morphing from a vertical rectangle towards a more horizontal one. Livan Hernandez's CG, 3-hit, 15 K game vs Atlanta (and Maddux btw) in the 1997 NLDS, and particularly his final K of Fred McGriff, was the poster child game and pitch for that era. The final strike would maybe have been behind a RH batter and Crime Dog couldn't have hit it with a canoe paddle but that didn't stop HP ump Eric Gregg from calling it. At this time the umpire union had yet to pull their ill-fated mass resignation strategy so were still very powerful and cohesive, some might even say arrogant. They were also pushing back against the gradual merging of the two leagues and so were taking the attitude that MLB couldn't tell them what to do because they weren't hired by MLB they were hired by the NL or the AL so the by then largely toothless League Presidents were the only ones who could. I remember one saying, quite publicly, that 'just because the ML Rule Book defines a strike this way doesn't mean that's My strike zone'. So back to Maddux. He and Glavine (and others) were control pitchers with lateral movement on their pitches (Maddux: cutter, Glavine change-up) who took advantage of the wider zone trend because they would have been fools not to. Would they get those same calls now? No, not with the technology that grades umps on every game, and not with a whole new generation of umps who came up in the post-AL/NL era. But they'd still live on the corners and would undoubtedly still be successful in whatever adjustments they'd make. They weren't getting calls that other pitchers didn't also get back then, they were just better and/or smarter than most about taking advantage of the times. This challenge system, if and when it gets here, isn't going to change much about how pitchers pitch or how hitters react. It's merely going to give the ability to review maybe a half-dozen pitches per game [two for each team plus more for every challenge won] and correct some of them.