If a manager communicated with and listened to their team, but their team had written a web service with gaping security holes or disastrous data integrity prac

If a manager communicated with and listened to their team, but their team had written a web service with gaping security holes or disastrous data integrity practices because all their senior engineers were incompetent and/or were hired at a level that was above their ability, would that manager find out just from chatting with them? I promise you that it's not guaranteed. You need to actually go looking through the code to find everything that's wrong.