BtB Power Rankings: Week 22 -- We're into September

Look!  A National League team in the top 5!

"On Paper" Playoff Leaders (*=new this week)

American League: E=Yankees*, C=Twins, W=Rangers, WC=Rays
National League: E=Braves, C=Cardinals, W=Padres, WC=Rockies

Under the Hood

Converting Runs to Wins

Click in the header to sort the tables

G=Games
RS = Actual Runs Scored, after a park adjustment
eRS = Estimated Runs Scored, after park adjustment (see table below)
RA = Actual Runs Allowed, after a park adjustment
eRA = Estimated Runs Allowed, after park adjustments (see table below)
W% = Actual Winning Percentage
pW% = PythagenPat Winning Percentage, based on actual runs scored and run allowed totals
cW% = Component Winning Percentage, using estimated runs scored and estimated runs allowed totals.  If you don't like the league adjustments or strength of schedule adjustments, click in the header and sort by this column to get an "unsullied" ranking.
SoS = Strength of Schedule.  This is an iterative weighted average of the component-based winning percentages of a team's opponents.  Described in this post.
cW%s = Schedule-adjusted Component Winning Percentage.  Calculated by applying SoS to cW% with the log5 method, as described in this post.
xTW = Extrapolated wins.  Based on current real wins to date, and extrapolated wins over the rest of the season.  Extrapolations are based on an average of cW% and cW%s, as justified in this post.
LgQ = League Quality.  The AL has superior talent to the NL (justification here and here, and modified most recently here.  A good introduction to the topic is this post).  The number shown is an estimated true talent level (in winning percentage) of the two leagues were they to be able to play one other for a large number of games.  It's based on the last two years of interleague, with a small adjustment toward 0.500 to account for the fact that the leagues do play one another and thus have already had a small effect on one another's performance.
TPI = Team Performance Index, a hypothetical winning % based on cW%s, after adjustment for league quality. Think of this as the W% we'd expect teams to have if they were all in one big league and were allowed to play 10,000 games vs. every team.

Team Offenses and Defenses

RS = Actual Runs Scored
eRS = Estimated Runs Scored: HitRns + EqBRR
wOBA = The Book's statistic, but park adjusted, and using data from both HitRns and EqBRR
OBP = On Base Percentage (Times on Base / Plate Appearances)
SLG = Slugging Percentage (Total Bases / At Bats)
HitRns = Base Runs-estimated runs scored, ignoring all base running, using the equation in this post.
EqBRR = Dan Fox's composite baserunning statistics from Baseball Prospectus, minus stolen bases since they are included in wRC.

RA = Actual Runs Allowed, after park adjustment
eRA = Estimated Runs Allowed: PitRns - Field
ERA = Straight-up Earned Run Average
FIP* = Fielding-Independent Runs, based strictly on K-, BB-, and HR-rates.  HR/FB rates are park adjusted using these park factors.
xFIP = Expected Fielding-Independent Runs from FanGraphs.  Like FIP, but with HR/Outfield Fly Ball rates regressed completely to league average.  xFIP is as predictive as any other DIPS-like stat.
PitRns = Pitching Runs Allowed, the expected runs allowed based on the average of FIP and xFIP.  Described in this post.
Field = Described in this post.  It is essentially an average of team UZR, DRS (minus rSB since I calculate catcher fielding separately), and BsRFld.  BsRFld is just difference between FIP-based runs allowed and park-adjusted Base Runs, and is a less direct approach of measuring fielding.  The fielding number also includes a catcher fielding statistic, based on SB's, CS's, WP's, PB's, E's, and this year catcher interference.  The catching methods are essentially those described here.  But I'm using B-Ref data this year, and so there are slight tweaks to the methodology, generally in ways that should lead to greater accuracy.  If you want to know, feel free to ask!
BABIP = Batting Average on Balls In Play.  Fluctuates at the team level with fielding, although park effects and chance events can have effects as well.