I love appeal plays. It rewards a heads up defensive team. They don’t happen very often. You get to see the umpire make a nice solo out performance. They are just fun all the way around.
Since I returned to umpiring 3 years ago, I have actually never called a runner out on appeal. Like I mentioned above, they don’t happen all that often in the bigs, but they do.
Case in point from the Nats/Cards game a few nights ago.
7.02 In advancing, a runner shall touch first, second, third and home base in order. If forced to return, he shall retouch all bases in reverse order, unless the ball is dead under any provision of Rule 5.09. In such cases, the runner may go directly to his original base.
Harper did not re-touch all the bases when he was running in reverse. This made him subject to being out on appeal.
Give Tim McCarver, friend of umpires everywhere, credit as he was on top of this the whole time.
Advancing and retreating around the bases is covered on page 9 of RuleGraphics.