Baserunners in Season Ticket Baseball have two ratings that determine their success when trying to steal:
1. "Steal" determines whether the runner "establishes a lead" ("getting a good jump" would also be an accurate description). To establish a lead, the runner rolls both ten-sided dice and adds their Steal rating. If the total beats the pitcher's Hold rating by 10 or more, the runner has established a lead and must attempt a steal.
2. "Speed" determines whether the steal attempt succeeds. The runner rolls all three dice and adds their Speed. If the total beats the catcher's Arm rating by 10 or more, the runner is safe.
(Note: The same method is used for stealing second base or stealing third base. Stealing home uses the same system, but greatly increases the difficulty by bumping the catcher's Arm rating up to 12.)
However, there's a third rating that I call "Aggression" which measures how often a player tries to steal. "Aggression" isn't shown on the card, but I am starting to include it with the ".csv" files included with each season.
Aggression has 5 levels:
0: Only try to establish a lead if Speed is 2+ points higher than Catcher's Arm.
1: Try to establish lead if Speed is 1+ point higher than Catcher's Arm.
2: Try to establish lead if Speed is equal or higher than Catcher's Arm.
3: Try to establish lead if Speed is within 1 of Catcher's Arm (or higher).
4: Try to establish lead if Speed is within 2 of Catcher's Arm (or higher).
So, for a runner with a Speed of 5:
With Aggression=0, they only try to establish a lead if the Catcher's Arm rating is 3 or lower.
With Aggression=1, they try to establish a lead if the Catcher's Arm rating is 4 or lower.
With Aggression=2, they try to establish a lead if the Catcher's Arm rating is 5 or lower.
With Aggression=3, they try to establish a lead if the Catcher's Arm rating is 6 or lower.
With Aggression=4, they try to establish a lead if the Catcher's Arm rating is 7 or lower.
How Aggression is Calculated
For each player, I iterate through all possible combinations of Aggression, Speed and Steal to determine the best ratings for their SB and CS totals.
Imagine a player with 0 Aggression, 6 Speed and 3 Steal. An Aggression of '0' means they only roll to establish a lead if the catcher's Arm is 4 or less. I then look at this player's opponents to find the Arm ratings of every catcher they will face and calculate the percentage of the time they will be on base against a catcher with an Arm of 4 or less. In a typical league this is about 35%.
I then count up all the pitcher Hold ratings to figure out how often a player with 3 Steal rating will successfully establish a lead. This is about 30%. Then I estimate the number of times the player will be in a steal situation (e.g. on 1st base with 2nd base empty). IIRC, this is about 110 for an average full-season batter.
110 x 35% x 30% = 11.55 successful times establishing a lead (i.e. 11.55 steal attempts)
I then calculate that 70% of these will be against an Arm of 4 (86% success chance) and 30% of these will be against an Arm of 3 (90% success chance) for a total success rate around 87.2%. So the 11.55 steal attempts will result in 10.07 SB and 1.48 CS.
What if I raise their Aggression to 2?
2 Aggression means they roll to establish a lead if the Catcher's Arm is 6 or less. This is something like 85% of catchers. A player with 3 Steal rating will successfully establish a lead about 30% of the time. Using the same 110 times on base:
110 x 85% x 30% = 28.05 steal attempts
I then calculate that:
3.4 attempts will be against an Arm of 3 (90% success chance)
8.1 attempts will be againts an Arm of 4 (86% success chance)
8.9 attempts will be againts an Arm of 5 (80% success chance)
7.6 attempts will be againts an Arm of 6 (74% success chance)
This results in something like 23 SB and 5 CS (82% success rate). So my total number of SB went up but my success rate went down (as one would attempt when being more aggressive). I do this for all combinations until I find the best Speed and Steal ratings for each player.