I'm finding quite a few teams that have DBs listed among ST Rushers. Unlike the McKeon rule, speed has nothing to do with whether or not it's a violation. One of the Gunslingers DBs has 64 speed and probably wouldn't block a punt.
In fact it doesn't even matter whether they block a punt or not, it's a violation just having them on the front 4, that's why I'm pointing out who needs to fix it now.