Base runs (BsR) is a baseball statistic invented by sabermetrician David Smyth to estimate the number of runs a team "should have" scored given their component offensive statistics, as well as the number of runs a hitter or pitcher creates or allows. It measures essentially the same thing as Bill James' runs created, but as sabermetrician Tom M. Tango points out, base runs models the reality of the run-scoring process "significantly better than any other run estimator". Purpose and formula Base runs has multiple variations, but all take the form Smyth detailed the following forms of the statistic: The simplest, uses only the most common batting statistics A = H + BB - HR B = (1.4 * TB - .6 * H - 3 * HR + .1 * BB) * 1.02 C = AB - H D = HR An offshoot includes significantly more batting statistics A = H + BB + HBP - HR - .5 * IBB B = (1.4 * TB - .6 * H - 3 * HR + .1 * (BB + HBP - IBB) + .9 * (SB - CS - GIDP)) * 1.1 C = AB - H + CS + GIDP D = HR A third formula uses pitching statistics A = H + BB - HR B = (1.4 * (1.12 * H + 4 * HR) - .6 * H - 3 * HR + .1 * BB) * 1.1 C = 3 * IP D = HR Other sabermetricians have developed their own formulas using Smyth's general form, mainly by tinkering with the B factor. Because the base runs statistic attempts to model the team run scoring process, a formula cannot be applied directly to an individual player's statistics. Doing this would result in a run estimate for an entire team that puts out the individual's statistics. A workaround for this issue is to find the team's base runs with the player in the lineup and the team's base runs with a replacement level player in the lineup. The difference between these values approximates the individual's base runs statistic. Advantages of base runs Base runs was primarily designed to provide an accurate model of the run scoring process at the Major League Baseball level, and it accomplishes that goal: in recent seasons, base runs has the lowest RMSE of any of the major run estimation methods. In