Excadrill is far from broken given the checks present to it (and the checks aren't even super specialized, they are useful in their own right). Weaknesses to common attacking types means it has some difficulty setting up, and at +2 it still has its checks.
Actually, it's this type of attitude that will keep Excadrill "in question," much like what is happening with Latios currently. Several rounds have passed, and ways around Excadrill have been discovered despite the initial hype. Some haven't moved past it and will continue to cry for its banning.But that's not the case so, he's always going to be in question both ways regardless of if he's banned or not, much like Latias was in early Plat.