It surprises me that according to xg roller++, 13/11 6/5 is virtually tied with 7/5 6/5 after 61-55. Normally, 7/5 6/5 tends to be better than 13/11 6/5 on the third roll after the 61 opening. I include a couple of other positions for reference. One where the opponent holds his three point just like he does after 61-55 (61-53), and one where he has a blitzing oriented position with a good race (and I have good timing for priming...), just like after 61-55 (61-66).
It seems to me that the blitzing character of the opponent's second roll play might be a factor...
Can anyone help me understand why 13/11 6/5 is so good after 61-55 (and 61-66) compared to in other 61-XX-21 situations?
         
 
         
 | | White is Player 2
score: 0
pip: 147 | | Unlimited Game | pip: 160
score: 0
Blue is Player 1 |
|
| XGID=-b----EBB---cD---c-e--b-B-:0:0:1:21:0:0:0:0:10 |
| Blue to play 21 |
| 1. | XG Roller++ | 7/5 6/5 | eq: +0,031 |
| Player:
Opponent: | 51,53% (G:15,00% B:0,64%)
48,47% (G:15,99% B:1,16%) | |
|
| 2. | XG Roller++ | 13/11 6/5 | eq: +0,030 (-0,001) |
| Player:
Opponent: | 52,32% (G:14,06% B:0,60%)
47,68% (G:16,83% B:1,44%) | |
|
eXtreme Gammon Version: 2.10
 
| | White is Player 2
score: 0
pip: 159 | | Unlimited Game | pip: 160
score: 0
Blue is Player 1 |
|
| XGID=-b----EBB---eD---b-d--b-B-:0:0:1:21:0:0:0:0:10 |
| Blue to play 21 |
| 1. | XG Roller++ | 7/5 6/5 | eq: +0,083 |
| Player:
Opponent: | 52,06% (G:16,13% B:0,73%)
47,94% (G:14,63% B:0,92%) | |
|
| 2. | XG Roller++ | 13/11 6/5 | eq: +0,046 (-0,037) |
| Player:
Opponent: | 52,01% (G:14,54% B:0,65%)
47,99% (G:15,40% B:1,13%) | |
|
eXtreme Gammon Version: 2.10
| | White is Player 2
score: 0
pip: 143 | | Unlimited Game | pip: 160
score: 0
Blue is Player 1 |
|
| XGID=-b----EBB---cD---abe---bB-:0:0:1:21:0:0:0:0:10 |
| Blue to play 21 |
| 1. | XG Roller++ | 7/5 6/5 | eq: +0,051 |
| Player:
Opponent: | 52,36% (G:15,56% B:0,83%)
47,64% (G:16,72% B:1,29%) | |
|
| 2. | XG Roller++ | 13/11 6/5 | eq: +0,040 (-0,011) |
| Player:
Opponent: | 52,90% (G:14,42% B:0,70%)
47,10% (G:17,69% B:1,57%) | |
|
eXtreme Gammon Version: 2.10