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Ok, I'll admit it, before this season I had never looked at or even heard of any base-running statistics. I am a baseball lifer, have been around this game for as long as I can remember being around anything yet it had never occurred to me that it would be possible to accurately measure base-running value with any number or set of numbers. I am still not yet convinced.
There is data available, however, that is well worth a look and may put us on a path to a world of reliable base-running statistics.
What the stats do:
Baseball Prospectus categorizes running statsinto SBR (stolen base rate) GAR (ground advancement rate) SBR (stolen base rate) HAR (hit advancement rate...sorry Rowbots, nothing to do with Handsomeness Above Replacement in this piece) and an overall BRR (base running rate).
Each of these statistics is calculated based on the number of opportunities each team or player had in each situation. Each time a runner is on first with nobody in front of him and a ground ball is hit that does not result in a hit or an error, that runner is eligible for a GAR. If the ball does go for a hit, it becomes a factor in HAR.
Baseball Prospectus keeps track of the bulk number of opportunities with GA_OPPS, HA_OPPS etc. The rates are determined by calculating the number of successful attempts at advancement in the given number of opportunities.
This method allows for each scenario of base-running to be measured as they also have an AAR stat that accounts for sac-fly's and the like and an OAR (other advancement rate) for advancement on wild pitches, passed balls, and balks.
What the stats DON'T do:
I am still a new subscriber to Baseball Prospectus and thus had a difficult time tracking down the exact details on how each rate number is calculated, and therefore am not certain if weights exist for varying leverages. Fangraphs has created a UBR (Ultimate Base Running) stat that attempts to do just this by giving a point value to different kinds of running situations based on the importance/leverage of each one.
What neither of these stats do though, so far as I can tell, is ballpark-adjust. I wanted to tackle this issues in part because I had been linked to these statistics on a few occasions in order to prove that the Colorado Rockies were actually a better running team than my eyes were telling me.
Indeed, the Colorado Rockies of 2013 ranked 3rd overall BRR. You know who placed first? The New York Mets. Yes, not one, but two Eric Young Jr. teams made the top three in base running rate. Why? My theory: big outfields.
The second place team on the list is San Diego, and if you look across the board at the other numbers, each of the top three shares their biggest lead over the rest of the pack in HAR. It turns out, guys go first to third or second to home a lot more often when the outfielders have to track the ball down in a grand meadow before throwing it in.
The Rockies had a negative SBR and were middle of the pack in terms of GAR but still rated near the top of the league largely based on their ability to advance on hits.
How to use the stat:
I wrote at the top here that I am not yet convinced these stats do a good job of accurately measuring base running and it's actual impact on the game of baseball. I stand by that while admitting that I need to do a bit more digging. While it definitely seems like BRR is way off base in terms of showing who the best teams/player on the bases actually are, it does contain useful information when taken into account with the other available numbers and looking across the league.
BRR and it's companions don't quite yet capture how good a team is but it does help shine a light on what a team does well. I'd like to get into more base-running stuff next week before jumping to the defensive side of the ball. I'd like to look more into Fangraphs UBR, and try to get some advanced numbers on particular players.
For now, I must conclude that the Rockies high BRR does not mean that they were actually a better running team than they appeared to me, but that they advance more than other teams due to the nature of their environment. The Rockies could (emphasis on could) be fueling that stat by going from first to third on low-leverage situations on balls hit into the vast open space that is the Coors Field outfield.