You could improve your board strength by playing 5/1 3/1:
When you look at the resulting position, you have a very bad distribution and the checker on your 11 point does not bear onto an open point.
Although it has been said “that backgammon isn’t a beauty contest”, the resulting position looks fragile and stacked. Imagine what would happen here if you rolled 66. Therefore, although this equalises board strength and reduces your blot count, the future does not look great after this move.
It looks like you will have to leave the blot on your 3 point where it is, so you consider bringing your builders closer with 11/6 7/5:
The issue with this play is now not only will any 1 be great for Black, but also if Black nearly escapes into the outfield without hitting, then Black will be in great shape, as Black will control most of the outfield.
Black runs into the outfield with any 6, as well as 42 and 52. That is 13 rolls, as 61 has already been counted as a hitting roll.
Giving Black so much control of the outfield is a bad idea.
As you have your 20 point anchor, you may decide that you simply want to improve your board with 11/4:
If you are hit, you can never be closed out as your 20 point anchor means you will always enter eventually. While that is true, and you would really like to make your 4 or 3 point, again Black has too many rolls that either hit or escape into the outfield.
Again, you have given Black control of the outfield.
If you play 20/18 11/6, although you have one less blot, again you have given Black control of the outfield.
In summary, you know that you should leave the blot on your 3 point where it is, and you must retain some outfield presence.
Consider 20/15 7/5:
Although you have duplicated Blacks 1’s to hit you in 2 places, the addition of 3’s to hit means that Black will hit you with 20 rolls. Note that 63 is not counted as an additional hitting number, as it is already included in the 20 rolls. Note, if Black rolled 63 after this move, then Black should hit 23/14*.
This makes your 6’s less awkward next roll, but is just too many good numbers for Black.
This duplicates Black’s 1’s to hit into places, thus reducing the total number of hitting rolls that Black has. Black will now hit you with any 1 plus 63 and 65. That is 15 rolls, 5 fewer than the previous move.
If you are not hit, you have a good outfield presence which will make it harder for Black to escape, and many of your rolls will be easier to play, especially 6’s.
This is the best move, and what makes it particularly interesting is that it leaves 3 blots, but it is still better than the alternatives, some of which leave no blots.