I think this one is tough. First of all, 13/3(2) looks awkward. Secondly, I don't quite understand why the swing between 13/3(2) and switching points is so large when we pass to the variants below.

              
 
              
 | | White is Player 2
score: 0 pip: 100 | | Unlimited Game | pip: 127 score: 0
Blue is Player 1 | |
| XGID=-aBBBBB------C-b--bd-bbbB-:0:0:1:55:0:0:0:0:10 |
| Blue to play 55 |
| 1. | Rollout1 | 13/3(2) | eq: -0.411 |
| Player: Opponent: | 36.74% (G:6.25% B:0.18%) 63.26% (G:12.04% B:0.53%) | Conf.: ± 0.014 (-0.425...-0.397) - [100.0%] Duration: 1 minute 02 seconds |
|
| 2. | Rollout1 | 13/8(2) 13/3 | eq: -0.504 (-0.093) |
| Player: Opponent: | 34.48% (G:6.01% B:0.17%) 65.52% (G:11.31% B:0.49%) | Conf.: ± 0.014 (-0.518...-0.490) - [0.0%] Duration: 1 minute 01 second |
|
| 3. | Rollout1 | 13/8(2) 6/1*(2) | eq: -0.511 (-0.100) |
| Player: Opponent: | 35.52% (G:4.36% B:0.04%) 64.48% (G:11.49% B:0.57%) | Conf.: ± 0.012 (-0.523...-0.499) - [0.0%] Duration: 51.8 seconds |
|
| |
1 1296 Games rolled with Variance Reduction. Dice Seed: 62908879 Moves: 3-ply, cube decisions: XG Roller
|
eXtreme Gammon Version: 2.19.211.pre-release
Variant 1:

              
 
              
 | | White is Player 2
score: 0 pip: 98 | | Unlimited Game | pip: 127 score: 0
Blue is Player 1 | |
| XGID=-aBBBBB------C--b-bd-bbbB-:0:0:1:55:0:0:0:0:10 |
| Blue to play 55 |
| 1. | Rollout1 | 13/3(2) | eq: -0.490 |
| Player: Opponent: | 35.24% (G:5.32% B:0.12%) 64.76% (G:11.68% B:0.49%) | Conf.: ± 0.010 (-0.500...-0.480) - [100.0%] Duration: 1 minute 39 seconds |
|
| 2. | Rollout1 | 13/8(2) 6/1*(2) | eq: -0.513 (-0.023) |
| Player: Opponent: | 35.79% (G:4.09% B:0.04%) 64.21% (G:11.38% B:0.57%) | Conf.: ± 0.008 (-0.520...-0.505) - [0.0%] Duration: 1 minute 24 seconds |
|
| |
1 2592 Games rolled with Variance Reduction. Dice Seed: 62908879 Moves: 3-ply, cube decisions: XG Roller
|
eXtreme Gammon Version: 2.19.211.pre-release
Variant 2:

              
 
              
 | | White is Player 2
score: 0 pip: 96 | | Unlimited Game | pip: 127 score: 0
Blue is Player 1 | |
| XGID=-aBBBBB------C-b---dbbbbB-:0:0:1:55:0:0:0:0:10 |
| Blue to play 55 |
| 1. | Rollout1 | 13/8(2) 6/1*(2) | eq: -0.635 |
| Player: Opponent: | 35.18% (G:2.99% B:0.03%) 64.82% (G:15.29% B:0.94%) | Conf.: ± 0.011 (-0.646...-0.624) - [100.0%] Duration: 33.7 seconds |
|
| 2. | Rollout1 | 13/3(2) | eq: -0.722 (-0.087) |
| Player: Opponent: | 32.99% (G:4.01% B:0.11%) 67.01% (G:16.77% B:0.87%) | Conf.: ± 0.013 (-0.735...-0.709) - [0.0%] Duration: 40.1 seconds |
|
| |
1 1296 Games rolled with Variance Reduction. Dice Seed: 62908879 Moves: 3-ply, cube decisions: XG Roller
|
eXtreme Gammon Version: 2.19.211.pre-release