While the 96-97 Mailman is definitely an amazing player in the sim, I prefer the 89-90. More efg%, way more trips to the line... but also he brings with him way more turnovers and fouls, so it's kind of like 6 of one, half dozen of the other. The big thing is the minutes... more minutes of the guy you focus your offense around is always a good idea.
Possession Battle: Solid rebounding. You don't have "that guy" to clean the boards but do have a nice aggregate total. That'll keep you competitive. Turnovers are kinda meh... not anything extreme one way or the other. You'll get some steals. Overall, I call it a wash.
Shooting Struggle: Defense is fine. Mailman, Parish & Harden all give you good stuff offensively. I don't care for Iggy that much but he doesn't hurt you too much. Oakley's usage is a little high to be optimal but I still dig it. Plenty of assists... you should be solid in the shooting struggle.
Foul Factor: Not the best Mailman at getting to the line... still, he's not bad at all. Harden gets there a ton for his usage. Reasonably low fouls with a good amount of trips to the line... good. You don't have much inside/outside extremes to really put the defense in a pinch, however, so I don't think you're really gaining a big advantage here, either.
Overall, you're not hurting in any of the three areas I think most important, but you're not dominating, either. It's a solid squad. This team could win 30 games or 50 games and I wouldn't be surprised.