Who are the best teams in the American and National Leagues? This year’s first installment of the Whisnant ratings answers the question as inter-league play begins.
As with last year, in the RS/RA rating system each team has an offensive and defensive rating that corresponds to the average number of runs scored and runs allowed per game, respectively, they would expect to have against an average team. A home field advantage factor is also included.
If Team A plays Team B, the number of predicted runs scored for Team A is the offensive rating of Team A plus the defensive rating of Team B minus the average number of runs per game for all teams, plus or minus the home field advantage factor (plus if Team A is at home, minus if away). The rationale for this formula is that a team will tend to score more runs than average in a particular game if they score more runs than average and/or the other team allows more runs than average.
A fit is performed to the scores of all major league games this year to find the values that give the smallest overall quadratic deviation (least-squares error) from the actual game results. Once the offensive and defensive ratings are determined, the overall rating is the team’s hypothetical won-loss percentage using Bill James’ Pythagorean formula (actually, I use the more refined Pythagenpat variant – see http://en.wikipedia.org/wiki/Pythagorean_expectation for a description).
Since inter-league play has not started, separate ratings will be given for each league. The AL RS/RA ratings through games of May 21:
| RS/RARank | Team | RS/RARating | Off | Def | W | L | Sch.Str.(Rank) | W/LRank |
| 1 | TOR | 0.600 | 5.34 | 4.33 | 27 | 17 | -0.13 (11) | 2 |
| 2 | DET | 0.594 | 5.45 | 4.48 | 23 | 16 | -0.01 ( 7) | 3 |
| 3 | BOS | 0.564 | 5.27 | 4.62 | 25 | 16 | -0.04 (8 ) | 1 |
| 4 | TEX | 0.531 | 5.36 | 5.03 | 23 | 17 | -0.24 (14) | 5 |
| 5 | TBR | 0.527 | 5.23 | 4.94 | 21 | 22 | -0.23 (13) | 8 |
| 6 | KCR | 0.514 | 4.32 | 4.19 | 21 | 20 | -0.14 (12) | 7 |
| 7 | NYY | 0.511 | 5.52 | 5.40 | 24 | 17 | -0.01 ( 6) | 4 |
| 8 | CLE | 0.501 | 5.62 | 5.61 | 16 | 26 | 0.38 ( 1) | 13 |
| 9 | LAA | 0.500 | 4.99 | 4.99 | 21 | 19 | -0.05 ( 9) | 6 |
| 10 | MIN | 0.479 | 5.22 | 5.45 | 19 | 23 | -0.06 (10) | 10 |
| 11 | OAK | 0.459 | 4.72 | 5.13 | 15 | 23 | 0.28 ( 2) | 12 |
| 12 | SEA | 0.413 | 3.86 | 4.63 | 19 | 23 | 0.01 ( 5) | 9 |
| 13 | BAL | 0.405 | 4.93 | 6.02 | 16 | 25 | 0.18 ( 4) | 14 |
| 14 | CHW | 0.397 | 4.05 | 5.03 | 17 | 23 | 0.18 (3) | 11 |
The AL home-field advantage factor is about 0.28 runs per game, and the average number of runs per game is 4.99 (which gives a Pythagenpat exponent of 1.94). Also shown are the actual W/L records, the schedule strength, and schedule strength rank. The schedule strength is given in runs per game, and represents the average difference between the offensive and defensive ratings of a team’s opponents.
Toronto has the best record and also the top rating, even though their schedule is relatively weak. Texas has had the easiest schedule in the AL, followed closely by Tampa Bay. Cleveland has the worst record, but is not the lowest rated team in the AL, thanks to the league’s toughest schedule so far.
The last column in the table shows the ranking using the W/L method, which takes into account only wins and losses. Boston, because of its tougher schedule, moves ahead of Toronto to take the top spot. New York, Anaheim, Seattle and Chicago also move up, while Tampa Bay and Cleveland drop significantly.
The NL RS/RA ratings through games of May 21:
| RS/RA Rank | Team | RS/RARating | Off | Def | W | L | Sch.Str. (Rank) | W/LRank |
| 1 | LAD | 0.639 | 5.40 | 4.00 | 29 | 13 | -0.37 (16) | 1 |
| 2 | MIL | 0.598 | 5.13 | 4.16 | 26 | 15 | 0.03 (9) | 2 |
| 3 | NYM | 0.551 | 4.89 | 4.39 | 21 | 19 | -0.03 (12) | 7 |
| 4 | STL | 0.551 | 4.79 | 4.30 | 24 | 17 | 0.08 (4) | 3 |
| 5 | PIT | 0.533 | 4.56 | 4.25 | 19 | 22 | 0.02 (11) | 11 |
| 6 | CHC | 0.528 | 4.84 | 4.56 | 21 | 18 | 0.05 (8) | 4 |
| 7 | PHI | 0.521 | 5.49 | 5.24 | 22 | 17 | -0.17 (15) | 6 |
| 8 | CIN | 0.514 | 4.63 | 4.50 | 21 | 19 | 0.08 (5) | 5 |
| 9 | COL | 0.493 | 5.21 | 5.29 | 16 | 24 | -0.04 (13) | 14 |
| 10 | HOU | 0.472 | 4.51 | 4.79 | 18 | 21 | 0.23 (2) | 8 |
| 11 | ATL | 0.466 | 4.09 | 4.40 | 20 | 20 | -0.13 (14) | 12 |
| 12 | SFG | 0.459 | 3.87 | 4.22 | 19 | 21 | 0.10 (3) | 10 |
| 13 | FLA | 0.453 | 4.59 | 5.06 | 19 | 23 | 0.05 (7) | 13 |
| 14 | ARI | 0.441 | 4.16 | 4.71 | 17 | 24 | 0.07 (6) | 15 |
| 15 | SDP | 0.410 | 3.89 | 4.71 | 19 | 22 | 0.25 (1) | 9 |
| 16 | WSN | 0.400 | 5.14 | 6.36 | 12 | 28 | 0.03 (10) | 16 |
The NL home-field advantage factor is only about 0.06 runs per game, and the average number of runs per game is 4.69 (Pythagenpat exponent 1.90).
Los Angeles has the best record and also the top rating, despite having had the easiest NL schedule. San Diego is next to last in the ratings, and they have had the toughest schedule as well. The NL Central has four of the top six teams in the league, while the NL West has three of the bottom five.
Los Angeles is also on top in the W/L rankings. Cincinnati and San Diego move up significantly compared to the RS/RA rankings, while New York, Pittsburgh, and Colorado move down.
These rankings track very well with the usual Pythagorean W/L prediction using actual runs scored and runs allowed (one version of the standard Pythagorean W/L expectation, updated daily, can be found on the MLB website at http://mlb.mlb.com/mlb/standings/index.jsp ). They differ since the teams do not play a perfectly balanced schedule. Also, you may have noticed that these ratings (which represent win percentages) don’t average exactly to 0.500, as you might expect them to. This is not necessarily due to round-off error — the usual Pythagorean win percentages don’t in general average to 0.500, either.
The rankings using Runs Created will be presented Saturday. The next update to the RS/RA and W/L rankings will be after inter-league play is completed on June 28, when the leagues will be combined into a single set of ratings.