That was because of pace. The whole way guys played D back then was different too. Folks have a bad idea that it was better, but it actually was just different. Guys iso'd way more back then, and good D was just making it harder for the guy to get his number, to make him work and get in his head. Guys like Dirk and Nash weren't particularly bothered by Bowen at all, but people remember him checking them because that's the standard for perimeter D the Spurs had. In the Medium Three era, they were able to demolish perimeter scorers in a way Bowen really didn't do. That's a lot to do with Green's and Leonard's talent, but it has a ton to do with how team defense had evolved too. Bowen-esque D just isn't important any more. The dirty play and mind games get techs and flagrants at a much higher rate. Now, rather than making guys work, teams focus on not allowing shots in efficient areas. That's why Murray is considered to be the Spurs' best perimeter defender despite White being a far better one-on-one defender.
Danny has a great argument against Bruce even before you add in things like transition D where Green is obviously better.