WAR (Wins over Average Replacement) is a complex formula comparison statistic used to judge a player's value relative to his peers. The object is to determine how much value a major leaguer has over a "replacement player," i.e. a AAA or AAAA minor leaguer.
How one player during a season affects one win over the collective play of the rest of his team is quite debatable; it is a misnomer to say Player X "wins" a specific game when there were 50 other players which he took no part in that were just as important in determining the outcome of the contest. Only if a pitcher who throws a perfect game could claim he alone was the reason for the victory, if he batted in the game winning run.
So WAR is more esoteric. It tries to compare a major leaguer's production over his potential replacement. Rarely does a minor leaguer come into the majors as an All-Star (however, there are exceptions to that rule like Mike Trout of the Angels this season). Even when a player starts off well in the majors, the league catches up to him.
The WAR scale is fairly simple. An 8 plus means a player is an MVP candidate. A 5 to 8 player is All-Star caliber. A 2-5 player is classified as a starter. A zero to 2 player is classified as a reserve or bench player. A player with a negative WAR is a replacement level player (in reality, if you can't be a reserve player then you are heading for one's release from the team.)
But the WAR stat does not give one an objective view of a player in relation to his peers. Baseball is a stat game with well accepted baseline performance numbers, i.e. a .300 hitter is classified as very good (the goal). Contact with the baseball is a key element of offense.
It may be more useful to actually compare players with their position counterparts to see how they really stack up. For example, we ran a stat screen of the Top Left Fielders in baseball, sorted by batting average. The top 15 LF have a WAR range of 4.4 to -0.4, so that makes that list the control group.
When you total up all the numbers for AB, H, HR, RBI and SB for the control group and divide by 15, you come to the baseline averages for LF players:
.283 BA, 19.67 HR, 68.33 RBI, 9.67 SB
With this baseline stat, you can easily compare it to your team's starting LF to see if he is above or below the norm for his position.
Since these four offensive categories are accepted as basic performance criteria, how many of the Top 15 LF actually exceed the baseline average? 8 players beat in BA; 7 beat in HR, 8 beat in RBI and 6 beat in SB. This confirms that the baseline averages is a good measure of what a quality LF player should be producing at the major league level.
You can further compare the baseline average with each individual player in the list of 15. How many players exceeded the average in all four categories? Only two. How many exceeded the average in three of the four categories? Four. How many exceeded the average in two of the four categories? Four. How many exceeded only one average category? Three. And two players on the list did not exceed any average category. (A 2-4-4-3-2 spread between 15 players again confirms that the baseline average is a viable comparison tool).
