The Mistake Index measures three broad categories--the pitching, base running and fielding mistakes teams make as well as their opponent's mistakes. It stems from my belief that good teams make fewer mistakes than bad teams, and this is my way of attempting to measure that. Click on the picture for a clearer view.
Blown Saves (BS), Hit by Pitch (HBP), Balks (BK), Wild Pitches (WP) and Passed Balls (PB) are precisely what they are. Errors in Pitching (EP) are those HBP, BK, WP or PB that directly allow a run to score--it does NOT measure, for example, if a balk allows a runner to advance to 2nd who is subsequently driven in by a single. In addition, any time a pitcher is walked is included. EP will by definition double-count the event that allowed the run to score, but that's the TRUE definition of a pitching mistake--truly giving away a run. Two-out runs (2oR) are my own special category I developed after watching a particularly difficult Cubs game (I know, how did I pick one) that has its own description.
Errors (E) and Unearned Runs (unER) are exactly what they are. These are gifts, and I wrote some time back on the relationship between errors and unearned runs. This makes it transparent--roughly half of errors turn into runs, making it in a team's interest to cut down on them.
BASE RUNNING MISTAKES
Base running mistakes (eBR) occur when players are thrown out trying to advance--it does NOT include force outs, since it's not a player's fault that a ground ball was hit directly to a fielder. Any fielder's choice in which a runner is thrown out is included (except to 1st). Errors in bunting (eBU) are any bunts that DO NOT result in a sacrifice or a hit with a runner on base--any bunt attempt with the bases empty is NOT INCLUDED, since that's bunting for a hit, and with teams batting around .380 when bunting, it's a good strategy.
The beauty of this index is that I also tabulate opponent mistakes--any HBP, balk, etc. by an opponent is a gift, any base runner thrown out removes a potential scoring threat and so on. The column in yellow is the difference between an opponent's mistakes and a team's:
If you take a look at the teams with positive numbers, they're generally having more success, and the teams with negative values, not so much. It's not perfect but it brings together many numbers that are either difficult to find or rarely seen together and puts them in one place.
STOLEN BASE INDEX
This used to be part of the index but I broke it off primarily to make the original index easier to read, and also because base stealing is a different facet of the game. No study I've undertaken suggests any correlation between base stealing and winning--sometimes teams win while being successful on the base paths, but it's often more correlation than anything else. The columns on the left (SB, CS, PO) are a team's stolen bases, caught stealing and pickoffs, and the columns on the right (oSB, oCS and oPO) are an opponent's. Net base stealing is:
Stealing bases, throwing out opponents stealing and picking them off are good events, getting caught stealing or picked off and letting opponents steal are bad. Positive values mean teams are more successful stealing than their opponents, negative less successful. It measures two very different things--stolen bases are controlled by a typically small number of players, and preventing stolen bases the primary responsibility of the pitcher and catcher. Again, this merely presents information that is either difficult to find or rarely in one place.
The Mistake Index isn't perfect, but it does allow a person to see many disparate stats that taken together can help explain team success. Error numbers may differ from official results due to changes in scoring which turn errors into hits and unearned runs into runs--I typically try to clean this up on a weekly basis, but the power of this Index isn't whether the White Sox have 96 errors or actually 94, but that they're 3rd in errors and that about 60% of those errors turn into unearned runs--if you can find that anywhere else, good for you.