One of the things that has defined the way the Rays have played the game of baseball is their aggressiveness on the basepaths. The past four years, the Rays have led the American League in steals. Are the Rays really the best baserunning team in baseball? How much has the Rays’ baserunning tendencies helped them win games?
In 2011, the Rays led the American League and ranked second in the major leagues with 155 stolen bases. However, they also led the major leagues with 62 stolen bases, and their 71.4% stolen base percentage ranked just 18th in the majors. The league average was 108 stolen bases, 42 caught stealings, and a 72.2% success rate. Sure, it’s nice that the Rays stole so many bases, but was it worth it?
Stolen bases aren’t just about success, but opportunity. In 2011, there was a correlation of -.308 between stolen base opportunities (SBO’s- plate appearances where a runner as on first or second base and there is no runner on the next base) and stolen base attempts (SBA’s). That means that there was a slight but undeniable negative relationship between SBO’s and SBA’s, meaning that teams that got on base more tended to attempt less stolen bases. That makes sense because the better hitting teams don’t have to worry as much about stealing bases to get into scoring position, although we see both from our experience watching baseball and from the low correlation that there are plenty of exceptions to that. The league average for SBA/SBO (let’s call it SBA%) was .0670 with a standard deviation of .0166. The Rays came in at .0956, or 1.72 standard deviations above the mean. A result that extreme or more only occurs in 4.2% of samples by chance alone, so we can say that the Rays’ SBA% is significantly higher than the league average. The Rays SBA% was the second-highest in baseball to only the San Diego Padres, and they actually led baseball in stolen base attempts. That the Rays went so often yet were so successful even when teams knew stolen bases were coming is pretty impressive.
But we know that baserunning isn’t just about stealing bases. It’s also about taking extra-bases, going 1st to 3rd and 1st to home on a double. The Rays 43% extra base taken percentage (XBT%), was a couple points above the 41% league average and ranked 7th in baseball. But that XBT% stat only tells you half the story. There are four possible outcomes when a runner is on base and the batter gets a non-home run hit: 1) the runner advances as many bases as the batter 2) the runner takes an additional base compared to the batter 3) the runner takes two additional bases compared to the batter because of an error or abnormal circumstance or 4) the runner is the runner is thrown out trying to take an additional base. What we need to do is compare extra bases taken to outs on the basepaths (attempting to take an extra-base). By that measure, the Rays ranked 8th in baseball in 2011. But four of the teams ahead of them were below average in terms of XBT% and only were successful at taking extra-bases because they ran the bases conservatively, so we can take those teams out. Only two teams in all of baseball, the Texas Rangers and Toronto Blue Jays, ranked ahead of the Rays in both XBT% and XBT success rate. The Rays were one of the best and most efficient teams in baseball at taking extra-bases.
The Rays not have been the best team baseball in terms of stealing bases or taking extra bases in 2011, but between their high standing in the two categories, they were the best baserunning team in baseball in 2011. But much does that actually help the Rays?
In order to figure that out, let’s use the Run Expectancy Matrix from Tom Tango. An average steal of second base is worth .078 runs and a steal of third is worth .035 runs while a failed stolen base attempt of second is worth -.042 runs and a failed stolen base attempt of third is worth -.08 runs (there are different run expectancy values for different base-out situations, but I’m not about to pedantically go through every stolen base attempt in MLB in 2011 to see in what situation each one occurred). For taking extra-bases, having 1st and 3rd as opposed to 1st and 2nd is worth .021 runs and 2nd and run scored as opposed to 2nd and 3rd is worth .2 runs. Getting caught trying to go 1st to third is worth -.25 runs while getting caught trying to score from 1st on a double is worth -.55 runs. Based on all that, the league average team in 2011 gained 23.4 runs on the bathpaths, or say 5.5 wins on the season. How about the Rays?
Summing up all the numbers, we get the shocking conclusion that the Rays were actually worth just 16.1 runs, or just 3.75 wins. How is that possible? This is a case where the Rays are basically confounded by their baserunning traits as they are more of a singles, steals, and home runs team (or at least they were in 2011) rather than a team that will hit a ton of doubles and get a lot of opportunities to go 1st to 3rd. What we have to do is neutralize a few things and do this whole thing again. After neutralizing 1st to 3rd and 2nd to home opportunities for the league average, their total runs gained shoots down to 12.3, or 2.87 wins. But there’s another thing that has to be done. This model assumes that the probability of the Rays stealing a base and the probability of the league average team stealing a base is the same. We know that’s not true. Let’s exchange the league average stolen base success rates for the Rays’ and see what that does. That brings it down to 12.0, or 2.81 wins.
The Rays are an above-average baserunning team. But it only net them one additional win compared to the league average in 2011. But when you think about it, that was enough. One more loss, and the Rays would have had to play a one-game playoff where anything could have happened. It’s worth being so aggressive on the basepaths because you never know when it can win you a game, and change the course of your season.
There’s also reason to believe the Rays will be even better in 2012. The Rays will Desmond Jennings in their lineup for the entire season, a healthy Evan Longoria who will swipe double-digit bags at a good percentage, and expect Reid Brignac to seize the shortstop job and steal four or five times as many bags as he did in 2011 (3). Appreciate the stolen base. Even when so many times it doesn’t pay off, at the end of the day it’s all worth it. Even the overaggressive failures that make you shake your head are meaningful. Aggressiveness is just one way that the Rays take advantage of every opportunity they get in order to win ballgames. You never know when that will matter.
Topics: Statistical Analysis