First, I think it's awesome that the BBs are taking the time to add new tactical options and I almost want to lose in the cup just to get the chance to try them out. That said, I have a few suggestions to make. Keep in mind that I haven't actually been able to use them yet due to my favourable cup draw, so I could be way off with these:
1) Implement them in private leagues. This would do a few thing: first, it would create a larger sample of games to draw conclusions from when it comes to balancing the new options. Second, it would allow people still in the cup to use the options. Finally, it would provide better feedback for this particular change since very few teams are running their best offensive player or best defender in scrimmages, while you often see the A teams lining up in PLs.
2) I was really hoping that the new options would allow you to choose what specific players you want to play specific roles, but the news article suggestions that it is just perimeter/inside options. I think it'd be better if you chose the exact player to perform each role. Due to substititions you would probably either have to set three player choices in a drop down menu or choose a specific position (i.e. the SF is always the "1" in the box and one/always double the opposing SF, or the C is always Isolated player). This would provide a lot more tactical versatility and reward interesting player and team builds. For example, you might want to isolate an outside shooting PF if you know the opposing team doesn't value OD on big men, or you might try to build a SF who is a great scorer inside and outside to try to take advantage of an opposing SF who is one dimensional (like when teams just play guards or big men at SF). It would also punish one dimensional defensive players. You could also come up with other tactics based on this like using a player in Iso sets who isn't your best inside scorer but is relatively good but very, very physical in an attempt to foul out the opposing team's star centre. Conversely, you might not want your "best" perimeter player playing as the "1" on defense against the best opposing player for fear of having that player foul out.
I do understand that coding could be a bit of an issue with this, though.