The Devil and Tim Kurkjian, they took a walk together

Posted on November 1, 2010

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If you watch Baseball Tonight on even a semi-regular basis, you are probably aware of analyst Tim Kurkjian‘s decade-long fixation on the sacrifice fly. Kurkjian loves sac flies: He has touted them in a book, and they make regular appearances in both his weekly KurkGems segment and his online columns.

Kurkjian, like most discerning baseball fans, appreciates the ability, reflected in the sacrifice fly, of a batter to get a runner home in a key situation when a runner is on third with fewer (not less) than two outs. Such a runner must not be stranded, and our admiration for the men who consistently make good enough contact to get that run home is understandable enough on its surface.

Unfortunately for Kurkjian and company, the sac fly turns out to be a bit of a baseball temptress. It beckons us with promises of selflessness, intelligence and pliability, admittedly admirable traits in any batter. But does it really help the batter’s team win?

Not often. If there are runners on second and third with one out, run expectancy matrices (which take the total number of times over the course of several seasons in which a given situation has arisen, then add up the number of runs that scored from that point until the end of the inning, then divide the latter by the former) tell us that 1.467 runs should score, on average, before the third out is recorded.

Of course, that number assumes average hitters, average pitchers and average conditions. Still, over the 40,000-plus occurrences on which it is based, that 1.467 seems a sound estimate.

If a batter in such a situation laces a single to center, he drives home two runs and gets himself to first base. Now the run expectancy is 0.573, but the two runs that crossed the plate must be accounted for. Thus, the batter has delivered to his team two runs, plus the new run expectancy, minus the old run expectancy. In total, his single was worth 1.106 runs above average.

What if that batter had gotten under his line drive, though? What if the center fielder had had to drift back, but had caught the ball with his heels on the warning track? Announcers would likely trumpet his ability to take a “good approach” and get the run home, with only slightly less vigor than that which they might have showed for the single.

But only one run scored this time, and the resulting state–runner on third, assuming the trailer advanced, with two out–is worth only 0.387 runs. 1.387, as your sixth-grade math teacher could help you discern, is less than 1.467. That sacrifice fly was actually a below-average outcome, by 0.080 runs.

Of course, not all sac flies are hit in that situation. In fact, there are eight total sac fly situations, if we cast aside the perhaps (and this is generous) one time per season that someone scampers home from second on a fly out: runner on third, runners on first and third, runners on second and third and bases loaded, with zero or one out.

It seems fair, if a bit optimistic, to grant that runners will usually advance from second to third on sac flies, but will rarely advance from first to second. Given all of these assumptions, which spots actually allow an average hitter to swat a sac fly without hurting the team?

With a runner on third and one out, or with runners on the corners and one out. That’s it. Only in those two of the eight situations does a sacrifice fly by an average or better hitter actually help a squad. Otherwise, when Carlos Lee hits a deep fly ball for yet another RBI, he is earning yet another empty RBI.

According to Baseball Reference, there were 1,300 sacrifice flies with a runner at third base this year (one came with runners at first and second). Of these, 299 came with only a runner on third; 410 came with runners on the corners; 244 were with runners on second and third and 347 happened with the bases loaded.

Unfortunately, I do not have access (and indeed, I do not know for sure who does) to information about how many of each came with zero and one out. Since 942 sac flies came with one away, though, against just 359 with no outs, we can gain a reasonable (if highly imperfect) approximation of that proportion by assuming that sacrifice flies happened 2.62 times as often with one out, regardless of the runners on base.

If that is true, or close to true, then here are our results, couched in terms of runs against average expectancy:

Runner on 3rd only: 12.4 runs gained

Runners on corners: 12.4 runs lost

Runners on second and third: 17.0 runs lost

Bases loaded: 40.6 runs lost

Not good. Only with a solitary runner on third do average betters do well to hit sac flies. Even then, the sac fly is a dangerous play. A runner does not merely get to take home plate by right on medium-depth flies; they can be thrown out, killing any chance of a rally.

Of course, if the batter at the plate is a slow-footed goon of a hitter who would probably just whiff or ground into a double play if he didn’t hit the sacrifice fly (here’s looking at you, Jonny Gomes), then a sac fly is a good thing. If you have your best hitter at the dish with runners in scoring position, though, you probably want more than a fly ball to score one run–making David Wright’s league-leading 12 sac flies this season a bit less impressive.

One of Kurkjian’s old sac fly favorites makes for a fun angle on this issue. Carlos Lee twice led the NL in sac flies and ranks tenth on the active leaders list for the category. Until 2010, though, he was a solid hitter on whom sac flies were wasted.

This season, he posted an ugly .246/.291/.417 line that made him below-average for the first time in his career and a more useful sacrifice flier–so, of course, he hit just four.

This is no harrowing indictment of the sacrifice fly. There is something to be said for turning expected runs into actual runs every chance you get, and you can ask Roy Oswalt and Juan Uribe about sacrifice flies in key moments. Still, it appears that Tim Kurkjian is leading us all a bit astray by constantly espousing the virtues of the noble RBI.

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