# Simulation Reboot Part 2

In order to properly simulate we need to know what happened in the past by actually counting it.   The difference in pitching innings between old era baseball and modern baseball is a problem.  We can’t simply dip into a game from the 1950s and pull a starter’s earned runs and innings pitched because starters pitch far less innings than than now.

DeltaWAA is the difference between an away team WAA and home team WAA where WAA is simply wins – losses.  League average across all deltaWAAs must equal 0 exactly because for every W a team receives, another team receives an L.  A standard deviation can be calculated however which means wins and losses can also be tiered like lineups, starters, and relief squads.

A tier as defined by this data model represents 1/2 standard deviation above or below league average.  A tier combo is an away team tier minus home team tier.  Negative tier combo means away team worse than home team and vice versa for a positive value,   In this data model tier combo are integers; each representing a set of values.

Below is a table showing home team win percentages for each tier combo set from  years 2000-2019.

### Tier Combo deltaWAA 2000-2019

TC Away% Home% Games Away R Home R
-6 0.248 0.752 929 3.608 5.473
-5 0.281 0.719 1070 3.817 5.524
-4 0.314 0.686 1984 3.845 5.235
-3 0.350 0.650 2871 3.960 5.130
-2 0.373 0.627 3479 4.152 5.029
-1 0.418 0.582 4077 4.355 4.769
0 0.465 0.535 4041 4.503 4.625
1 0.491 0.509 3921 4.632 4.472
2 0.547 0.453 3335 4.819 4.288
3 0.580 0.420 2872 5.048 4.155
4 0.607 0.393 1842 5.221 4.105
5 0.640 0.360 1089 5.488 4.134
6 0.713 0.287 999 5.710 3.869

Home team wins 75% of games at tier combo -6 which one would expect.  Away team wins 71.3% of the time with tier combo +6 when they have max advantage over home team.  The Games column shows the number of games in each tier combo set.  The last two columns show run differential per game that led to the win percentages.

Tier combo 0 is even steven between the two teams according to wins and losses.  Win% at TC 0 is almost exactly equal to overall home field advantage win% as one would expect.  The above represents what actually happened the last two decades with values that will be used to test the accuracy of the new simulator.

Not sure if or when baseball will resume.  Next part to this series will cover lineup -> starter and lineup -> relief tier combos through the various eras of baseball.  Right now we’re separating data into 1950-1969 , 1970 – 1999, and 2000 – 2019.  Eventually this simulator will look back to 1920 – 1949.  More on this later.  Until then ….