Or we just reduce their speed to F/B speed (-2). Inties can keep up better, but not too well until the turn. Static flak now stops them. Mobile flak hits them on the turn. Take longer to reach target = more time to react, more time on radar.
The unit isn't broken, it's just a bit out. IMO it will only take some small tweaks to a few digits here and there to make them totally fine.