Projected service holds are absolutely critical to trading a match correctly. If you don’t consider them, or interpret them incorrectly, then in my opinion you will not enjoy much success in tennis trading.
When calculating a projected service hold, my model will calculate court speed, the likelihood of surface holds and breaks for both players, the sample size, and relate this to the ATP or WTA mean. This gives us a pretty reliable estimate of the percentage of times a player will hold their serve and we can then relate this to the mean amount for each tour.
Some average stats (at the time of writing) are shown in the tables below:
ATP hold stats
Percentage hold ...