Thursday, April 28, 2011

Potential Runs Scored Percentage


Brendan Bowes got me thinking about something I hadn't really thought of before.  He put out the idea that there should be a way to measure the amount of times teams plate their runners on base.  It seems really basic, but when going searching for such a simple statistic, I found that it only sort of exists on Baseball-Ref.

Going with this idea, I have worked out a formula for this statistic, calling it "Potential Runs Scored Percentage(PRS%)."  This statistic calculates the amount of players who reached first, second or third base(as the direct result of their own plate appearance), who actually scored a run while on base.  On base results include a walk, single, double, triple, fielder's choice, hit by a pitch and reached on an error.  I do not include home runs because this statistic is trying to put a percentage on the number of guys who got on base and scored later.

The formula reads this way: Runs-HR/OBP(PA)-HR.  By subtracting HR from Runs Scored, you eliminate the players' runs who hit a home run, but it allows you to keep the runs scored by the runners who were on base in front of the home run hitter.  By subtracting home runs from the result of team OBP times team PA, you eliminate all of the hits that were home runs.  

There are other statistics that measure things like batting average with RISP, Runs Created, and even a statistic called Run Scoring %.  I only stumbled onto the last statistic after diving deep into Baseball Ref's "More Stats" section.  It is apparently similar to what I have here, except they do not count players who reached on fielder's choice or errors.  I think mine is more complete, even if it only includes a few extra players on base.

Here is a list of MLB's Potential Runs Scored Percentage(PRS%) team leaders in order:

                      Rank             Team          Potential RS %
                         1             Rangers               35.9
                         2              Indians               34.9
                         3             Yankees              34.2
                         4              Rockies              34.0
                         5               Reds                 33.7
                         6              Astros                33.6
                         7               DBax                 33.6
                         8              Orioles                33.0
                         9              Royals                32.6
                        10              Mets                 32.4
                        11             Phillies                32.0
                        12             Tigers                 31.3
                        13            Cardinals              31.1
                        14             Marlins                30.7
                        15               Rays                 30.5
                        16            Blue Jays              30.4
                        17              Braves               29.7
                        18            Mariners               29.1
                        19            Nationals              29.0
                        20             Brewers               28.9
                        21             Red Sox               28.3
                        22             Dodgers               28.2
                        23               Cubs                  28.1
                        24              Giants                 27.6
                        25               Twins                 27.3
                        26                 A's                   26.6
                        27               Angels                26.5
                        28            White Sox              26.4
                        29              Pirates                 26.2
                        30              Padres                 21.1

The Rangers are the best team at plating runners who reach base.  As I already suspected, the White Sox are the worst in the American League, and the third worst in MLB.  In yesterday's game against the Yankees, the White Sox loaded the bases with no outs, and failed to score a run.  The top four teams in Potential Runs Scored Percentage(PRS%) are all in first place.  I have always felt that the number one, most important statistic in baseball is runs scored; you can't win if you don't score.

To find differences in my statistic against Baseball-Reference's Runs Scored %, mine has the White Sox plating runners 26.4% while Baseball-Ref has them plating 29%.  For teams close to the top, the statistics are closer.  Mine has the Rangers at 35.9, the Indians at 34.9; BR's has the Rangers at 36% and the Indians at 35%, since they round up or down.  After studying the chart, it looks like 30.5% is the league mean.

Brent Morel has been the best for the White Sox individually of people with at least 60 plate appearances, scoring 43% of the time he gets on base.  Lillibridge has scored 63% of his times on base, but hasn't played a lot.  The least likely person to score after reaching base this year is Adam Dunn, who has scored only 9% of his times on base.

The Padres have been abysmal in run production this year, and they find themselves way at the bottom of the list by more than five percent less run production behind the Pirates.  Slightly off topic, a really amazing statistical anomaly has gone on with Dustin Moseley in particular of the Padres this year.

He has made five starts.  In his first four starts, the Padres gave him one run of support.  He has pitched lights out all year, giving up three or fewer runs in all of his starts, posting an ERA of just 1.99.  He is 0-3 with 2 no decisions.  He pitched one game where he allowed no runs, and two games where he allowed just one run.

To bring this back on point, it kind of sucks to pitch like this for a team who can't plate the runners that get on base.  It hasn't been quite as bad for John Danks this season, but he's had his taste of a lack of run support.  That's just fine, though, because he values a Quality Start higher than a Win anyways.

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