If it’s important to JoeyMVP shouldn’t it be important to you?

On Monday, Joey Votto appeared on Lance McAlister’s show (listen to the full podcast here). A fan asked Votto if there was an individual statistic that he looked at as the most important. The first baseman’s reply “weighted runs created plus” sent the hearts of sabermetrics fans aflutter.

With not much else is going on right now — Reds pitchers and catchers report on February 14 — here’s a primer on wRC+. Think of it as a bit of statistical spring training for your mind.

As Votto said, wRC+ stands for weighted (w) runs (R) created (C) plus (+).

The starting point in understanding wRC+ is that its focus is on runs, not hits.

Richard from Springboro would quickly point out that we already have ways to measure runs, published every morning in the box score. “Runs” (R) indicates the number of runs a hitter scores and “runs batted in” (RBI) indicates how many runs the hitter knocked in. They are fine counting statistics, but they only go so far.

The problem with R and RBI is they don’t do a great job of isolating the role of every player in contributing to the run. Not all the credit for a run scored should go to the runner who scored it and not every RBI is fully earned by the hitter.

RBI as a counting statistic leaves a lot of contributions out on the field and out of the box score. For example, suppose Player A doubles with Player B at first and Player B gets to third base. Then Player C hits a ground ball to third base, scoring Runner B. In that situation, all three played a vital role in scoring that run.

In the morning box score, Player B gets credit for the R, player C gets credit for the RBI. But Player A’s role is discounted. Without the double, player C’s ground ball could have started an inning-ending double play. Player C gets the RBI but is really fair to say that Player C contributed more to creating that run than Player A?

Enter Bill James. “Runs created” (RC) attempts to more accurately isolate the contribution of every player to a run being scored. Bill James created the statistic RC as a way to quantify how many runs resulted from what a player did with the bat and on the base path, including advancing runners. RC factors in positives like hits, walks, successful stolen bases, getting hit by pitches, sacrifice flies, sacrifice bunts, as well as negatives like grounding into double plays and being caught stealing.

Runs Created (RC) is the foundation of wRC+. The next component of wRC+ comes from Tom Tango who refined the concept of weighting while devising his own statistic “weighted on base average” (wOBA).

Weighting at bats means valuing them based on their actual power at producing runs. It means treating doubles as better than singles, triples better than doubles and singles as better than walks. Sometimes a “walk is as good as a hit” but sometimes it isn’t. Not many runners score from second base on a walk. (That doesn’t mean the walk in that situation has zero value, only that it has less value than a single.)

The weights are calculated based on actual measured outcomes in major league games. For example, how many runs does the average double create? Say 1.24. The average triple created 1.56 and a home run 1.95. The numbers account for runs directly driven in, runners advanced and runners put on base.

When you incorporate Tango’s concept of weighting into James’ formula for isolating contribution to runs, you end up with wRC. The output is a counting stat, like 76 — meaning the hitter created 76 runs.

Counting stats are great, but they aren’t easy to put into context in relation to other players in the league or across time. How do the 24 home runs Joey Votto hit in 2013 compare to the 35 that Todd Helton hit in 1999 or the 20 that Tony Perez hit in 1976? Counting stats are also vulnerable to misunderstanding due to injury. Lower counting stats may be due to a player spending part of the season on the DL, not the result of lesser performance.

That brings us to the plus. The plus means that the statistic has been normalized across an entire league and takes into account ballpark factors. It’s designed to let us see how Joey Votto’s 2013 compares to Tony Perez’s 1976. The plus also means the counting statistic has been converted to a rate-statistic, one based on a 100 point scale. Every point above 100 equates to being a percentage point better than average. A wRC+ of 125 indicates a player is 25 percent better at creating runs than the average player.

The plus isn’t solely used in connection with runs created. OPS+ converts OPS to a 100-point scale. ERA+ converts ERA to a 100-point scale. Here, wRC+ converts the counting statistic of wRC (129 for Votto ’13) to a 100-point scale (156 for Votto ’13).

Bottom line: wRC+ measures the impact that a hitter’s performance had on runs created. It isolates the player’s own contribution including advancing runners. It factors in the benefits of hitting with power, credits walks (but singles are worth more) and base running. It takes into account ballpark factors and allows the comparison of players across time.

When Votto holds up the mirror of wRC+ what does he see?

Votto’s career wRC+ is 156. His last four years (2010 – 172; 2011 – 157; 2012 – 178; 2013 – 156) are revealing and provocative. Votto’s “controversial” 2013 season was career average in terms of wRC+ but also below his previous three years. He was second in the NL, tied with Paul Goldschmidt and behind Jayson Werth.

Interestingly, Votto’s best season for wRC+ was 2012. Does that discredit wRC+ since that was the year Votto was hurt and didn’t hit a home run the last three months of the season? Not at all. Remember how well Votto had hit for three months prior to the injury? He finished second in the NL in doubles despite missing more than two months. Votto also had an OBP of .505 after returning from the DL.

Brandon Phillips’ wRC+ for 2013 was 91.

Despite its attributes, wRC+ is just one statistic. You’d be better off looking at several meaningful measures when evaluating a player. And wRC+ doesn’t incorporate defense, like WAR. But as offensive statistics go, there’s good reason that wRC+ has won Joey Votto’s heart.