Generally I think you're never going to get a 2B to throw to first instead of second unless they're right there, but your statement seems to argue against itself. If the chances of a double play are nil, then certainly you get the lead runner.
You'd have to very intentionally be aware of runner speed and decide ahead of time you were going to try 1B first, and that's probably too much to keep in your head when you get a grounder and have a split second to decide what to do.
I was wondering myself if Turang's arm was to blame, as you can see the difference when Willy relays vs him, but it sounds like it's the balls to Turang that don't get converted, not vice versa.