This is the first of many posts to describe WAA and its usefulness. A theorem is a statement that must be proven through other theorems or by statements of reasoning. We’ll start this journey by stating two theorems. These may be self evident or obvious but they need to be stated.

## Theorem 1:

**Sum (W-L) of all teams = 0**

There are mathematical symbols that represent this better but it’s simpler to explain this more verbally in this blog format. The above theorem states that adding up the formula (W-L) for all teams across the league will equal 0. This theorem basically states that for every team that wins, a team must lose, thus:

**Sum(W) across all team = Sum(L) across all teams**

This would not be true treating AL and NL leagues as separate entities. With current inter league play, an AL team can beat an NL team and a win would accumulate on the AL side incurring an NL loss. Before inter league play the above theorem would hold for each league.

## So what is WAA?

Theorem 1 specified (W-L) for teams. WAA is (W-L) for players. The value represents the amount of (W-L) that player brings to his team. A positive value means that player brought more wins than losses and has helped his team, a negative value means that player caused more losses than wins and has hurt that team. A player hurts his team by dragging it down from an average 0.500 season. Helping a team means a player pushes his team above a .500 record. A **WAA=0** means that player has performed completely average; neither helping nor hurting his team. Players who post zero WAA are not necessarily bad unless that team is spending significant money to that player. It’s perfectly acceptable for an average player making average salary to have a 0 WAA. Even negatives are fine for some position players like pitchers and catchers where hitting and power are sometimes sacrificed for defense.

So this leads to the next theorem.

## Theorem 2:

**Sum (WAA) across all players = 0**

The above theorem is used as an integrity check for the data model. By adding up all player WAA the result should be 0. If not, something is wrong with the model software. Since WAA value is conserved, for every positive point someone gets, one or more players must suffer negative points. In 2013 Clayton Kershaw of LAN posted an 11.8 (see here). There are about 12 players who suffered -1 or 4 players -3 to balance Kershaw out. Like in the team situation, in WAA there are winners and losers.

That is all for today. This is the first of many parts to explaining WAA. Feel free to peruse the various tables in other posts and career pages. More posts will be example data dumps to provide context into what this WAA number really means. Until then ….