Why do coaches hold a runner on 1st when a runner is on 2nd?
I don't see it a lot.
When I do see it, I assume they're trying to keep the double play in order. But it makes no sense. With r1/r2 (a runner in scoring position), the priority becomes keep-the-ball-in-the-infield/avoid-the-big-inning. Yet, they've got three infielders playing out of position (the first baseman, plus the two MIFs cheating in and towards the bag).