XGID=-b----E-C---dF--ab-ca-b-A-:0:0:1:51:3:1:0:5:10
Match Play. Red leads 3-1 to 5. How should Red play 51?
Whichever play Red selects, at this score, he will be doubled.
What he needs most is an anchor. Equally well he wants to strengthen his home board. 13/8, 6/5 attempts to achieve either one objective or the other.
The play also duplicates fours very nicely. Any play other than 13/8, 6/5 is an outright blunder.