Another gem from the boys at I Remember Dome-Dogs:
Earlier this week, I lambasted Cecil Cooper for calling on JR Towles to sac bunt in the 8th inning against Brian Fuentes. To make my case I utilized a statistic known as Run Expectancy (along with Win Expectancy, but I won’t be using that today). Well, today I’m going to pick on Cecil again. This time for his over aggressive base running and will try to make my case with Run Expectancy.
Courtesy of ESPN, the Astros have a SB% of 80% (24/30) which, on the whole doesn’t seem that bad. But lets break that down a little bit to get at what is bugging me. Michael Bourn is 13/13 in steals this year, so if you exclude him, we’re suddenly 64.7% (11/17) in SB%. Not so good. If we want to get really crazy, we can exclude Lance Berkman who some how is 4/4 in SB this year, which further reduces the Astros SB% to 53.8% (7/13). That’s not good.
All this begs the question, how bad has this been or how bad is this really? If you read the first article I wrote, we saw the sheer value of the out as far as Run Expectancy is concerned (or at least I hope I made my case). However, aside from quoting numbers from certain game states, the famed sabermetrician Tom Tango, has expounded upon the concept of Run Expectancy, devising linear weights. Tangotiger, as he is affectionately known, has done a lot of work looking into how runs are created utilizing linear weights and most of it is stuff I won’t ever pretend to really understand. However, he has provided general measurements for the run creating effects of every single offensive outcome in baseball. Using this data, we can come up with an approximation for just how bad our 53.8% SB% for non-Bourn/Berkman Astros has been for the team, as well as what the continued costs to run production could be if such aggressive base running tactics are pursued.
A stolen base (SB), according to TangoTiger, is valued at .19 of run, purely because it moves the runner over. This the marginal effect that a stolen base has on run expectations. The flip side, getting caught stealing (CS) has a value of -.44, meaning that it marginally reduces the run expectation by .44. We can break the CS run value up further, by looking at how it reduces the run expectations. It has an “inning-killing effect” of -.16 and a “moving the runner over effect” of -.02. The other -.26 is the "getting on effect" because creating that out reduces the likelihood that the next batter gets on, given that he has less outs to work it.
At face value, we can see that stealing bases is a bad proposition because the marginal benefit exceeds the marginal costs -- unless you have a “sure thing.” Like Michael Bourn. But back to what has our SB% for non-Bourn/Berkman players done to the team in terms of run-production.
Doing so simple multiplication, we discover that so far this season, when Cecil Cooper has called for a non-Bourn/Berkman Astro to steal a base, he’s reduced run expectations by 1.31. runs (1..33 for SB + -2.64 CS). While that -1.31 marginal run value doesn’t seem all that important, think of it this way: I’ve already projected the Astros to score about 5.1 runs/game on average through out the season, which means we’ll average about .6 runs per-inning (5.1/8.5 for the consideration that that last half inning isn’t played often times). If .6 runs per inning is what we expected to produce, then losing .10 runs (the -1.31 run value divided by the 13 attempts at stealing) on shoddy base running cannot be afforded, because that’s is a 1/6 our offensive production per inning right there.
I say run Michael Bourn up and down the field, he has the kind of speed and acceleration that track stars dream of so he’s a low-risk, high-reward baserunner. The rest of the team (except for the Big Puma, who’s decided to exhibit puma-like traits on the base paths this year) hasn’t done so well. I can’t say whether it’s ability or bad play calling, so I’ll assume it’s some combination thereof. Thus if the Astros are going to continue to score runs, they can’t survive on some how producing 52 2-out RBI’s in 22 games. Instead, their manager will have to be a little more prudent in how he gets his team to manufacture runs.