Here are the complete numbers for the 4 deck, S17 game.
Probability of a double down opportunity: 0.0952521
Average probability of win/push/loss: 0.552009, 0.0695503, 0.380259
The first column shows the player's total, the second the dealer's up card, the third the probability of this particular combination being dealt, the last three columns show the probability of the player winning, pushing or losing.
Hard doubles
9, 3, 0.00271311, 0.500195, 0.0688886, 0.430916,
9, 4, 0.00271311, 0.51841, 0.0664769, 0.415113,
9, 5, 0.00271311, 0.536646, 0.0641685, 0.399185,
9, 6, 0.00271311, 0.552803, 0.0622446, 0.384952,
10, 2, 0.00314605, 0.554506, 0.079036, 0.366458,
10, 3, 0.00314605, 0.569135, 0.0766647, 0.354201,
10, 4, 0.00314605, 0.584117, 0.0738528, 0.34203,
10, 5, 0.00314966, 0.60001, 0.0708573, 0.329132,
10, 6, 0.00314605, 0.614227, 0.0683477, 0.317426,
10, 7, 0.00314605, 0.564752, 0.0736985, 0.36155,
10, 8, 0.00314605, 0.536796, 0.0730063, 0.390198,
10, 9, 0.00320378, 0.49388, 0.0869117, 0.419209,
11, 2, 0.00363672, 0.583131, 0.0775646, 0.339304,
11, 3, 0.00363672, 0.596393, 0.0751123, 0.328494,
11, 4, 0.00363672, 0.610303, 0.0727347, 0.316962,
11, 5, 0.00363672, 0.624988, 0.0699342, 0.305078,
11, 6, 0.00363672, 0.637111, 0.0664188, 0.296471,
11, 7, 0.00363672, 0.580056, 0.0735837, 0.346361,
11, 8, 0.00363672, 0.550088, 0.0740865, 0.375825,
11, 9, 0.00363672, 0.520139, 0.0731223, 0.406738,
11, 10, 0.0136244, 0.509769, 0.0682111, 0.42202,
Soft doubles
13, 5, 0.000923611, 0.514469, 0.0444979, 0.441033,
13, 6, 0.000923611, 0.525947, 0.0441305, 0.429922,
14, 5, 0.000923611, 0.514255, 0.0438567, 0.441888,
14, 6, 0.000923611, 0.525781, 0.0433085, 0.43091,
15, 4, 0.000865885, 0.526253, 0.0485226, 0.491891,
15, 5, 0.000923611, 0.51293, 0.0429624, 0.444108,
15, 6, 0.000923611, 0.524377, 0.0435193, 0.432103,
16, 4, 0.000923611, 0.492188, 0.0450182, 0.462793,
16, 5, 0.000865885, 0.545138, 0.0460823, 0.475446,
16, 6, 0.000923611, 0.526075, 0.0421066, 0.431819,
17, 3, 0.000923611, 0.47541, 0.0789189, 0.445671,
17, 4, 0.000923611, 0.493476, 0.0764925, 0.430032,
17, 5, 0.000923611, 0.514827, 0.0731548, 0.412018,
17, 6, 0.000865885, 0.558661, 0.0878082, 0.420197,
18, 3, 0.000923611, 0.50589, 0.0783217, 0.415789,
18, 4, 0.000923611, 0.525981, 0.0754427, 0.398576,
18, 5, 0.000923611, 0.540267, 0.0737333, 0.385999,
18, 6, 0.000923611, 0.560983, 0.0697132, 0.369304
I hope these numbers are useful for some people. They confirm that if you are not winning at least half of your doubles in a large enough sample, then there is definitely something fishy going on.