Politics shares at least a little bit with baseball — at least in the sense that to get something done politically, you’ll occasionally need to rely on your backup.
You see this in the theater, as well. Eventually you’ll find that the main player isn’t available for some reason, so an understudy will step into the spotlight to carry the load for a while. The education industry has known this for years. When Ms. Reliable can’t make it one day, her students don’t have to spend the day staring at the wall. Ms. Substitute (or Mr. Substitute) is only a phone call away. Class will be back in session shortly.