Clearing the 10 pt seemed right to me, but I rolled out the positions a few times, and it became clear that the hits on the 13 pt are very good for white -- either for timing improvement or for going forward. In order for clearing the 10 point to be right, white must have a lot more timing, as in the following position:
         
 
         
 | | White is Player 2
score: 0
pip: 160 | Unlimited Game
Jacoby Beaver | pip: 90
score: 0
Blue is Player 1 |
|
| XGID=-ABbBbEB--B--Aba-aabbaa---:1:-1:1:63:0:0:3:0:10 |
| Blue to play 63 |
| 1. | XG Roller+ | 10/7 10/4 | eq: +0.469 |
| Player:
Opponent: | 67.91% (G:25.86% B:0.33%)
32.09% (G:2.91% B:0.07%) | |
|
| 2. | XG Roller+ | 13/4 | eq: +0.455 (-0.014) |
| Player:
Opponent: | 67.37% (G:26.12% B:0.36%)
32.63% (G:3.13% B:0.08%) | |
|
| 3. | 3-ply | 13/7 10/7 | eq: +0.346 (-0.123) |
| Player:
Opponent: | 64.18% (G:24.25% B:0.53%)
35.82% (G:4.33% B:0.12%) | |
|
| 4. | 1-ply | 7/4 7/1 | eq: +0.169 (-0.300) |
| Player:
Opponent: | 58.44% (G:23.95% B:0.42%)
41.56% (G:6.47% B:0.24%) | |
|
| 5. | 1-ply | 13/10 7/1 | eq: +0.165 (-0.304) |
| Player:
Opponent: | 58.06% (G:25.13% B:0.42%)
41.94% (G:7.02% B:0.32%) | |
|
eXtreme Gammon Version: 2.10
Improve white's board, and 13-4 is again correct by a large margin, even though white now has timing.
| | White is Player 2
score: 0
pip: 161 | Unlimited Game
Jacoby Beaver | pip: 90
score: 0
Blue is Player 1 |
|
| XGID=-ABbBbEB--B--Aba-aabbb----:1:-1:1:63:0:0:3:0:10 |
| Blue to play 63 |
eXtreme Gammon Version: 2.10
Part of the problem is that the 5-3 is just not that good a backgame. A change to a 4-5 holding/backgame yields a different result.
| | White is Player 2
score: 0
pip: 159 | Unlimited Game
Jacoby Beaver | pip: 88
score: 0
Blue is Player 1 |
|
| XGID=-ABBbbEB--B--Aba-aabbb----:1:-1:1:43:0:0:3:0:10 |
| Blue to play 43 |
eXtreme Gammon Version: 2.10