Additional Contributors to Rising Strikeouts

Baseball fans, generally, are aware that strikeout rates have been increasing over the period of several years. I wouldn’t say they’re yet “out of control” — it’s not like we’ve got a league of Mark Reynolds against Billy Wagner — but some people have raised some concerns, and, additionally, they’re still trending up. There’s no telling how high the strikeout rate might go. Craig Kimbrel just became the first guy to strike out more than half of the batters he faced in a season. I suspect it won’t be too long before we see another, or at least before we see someone come close.

On Thursday, we discussed evidence that home-plate umpires might be getting better at calling the strike zone. It stands to reason that could be a factor in the rising strikeout rates, since more strikes means fewer balls and you don’t need me to explain this to you, but we covered only the last few years, and also there are presumably a bunch of reasons for the hike we’ve observed. It’s not like it’s all about the umpires, just. Everything in baseball is complicated, and so examining this ought to be complicated.

Now, obviously, there are some clear factors at play. I don’t need to go into depth. Pitchers appear to be throwing harder than ever before. Hitters appear to be more willing to accept striking out than ever before. The former might be due to improved training techniques; the latter might be due to improved baseball analysis. I told you this would be complicated. There’s more, too, and there’s more still pasted below. I hope you’re wearing your table-of-data pants. If not, I hope your current pants are versatile.

Over at Baseball-Reference, I was able to track down pitch data covering the last 25 years, or, since 1988. That seems to be as far back as one can go — whenever I try to access 1987, I get an error. So, I’m satisfied with what we have. What follows is a big giant table, and if you’re curious about the headers, Strike% refers to Strike%. AS/Str% refers to rate of swings at strikes. Contact% is Contact%, 1stStr% is first-pitch-strike rate, 0-2% is the rate of plate appearances that get to an 0-and-2 count, and K% is K%. Sorry for all the numbers.

Year	Strike%	AS/Str%	Contact%	1stStr%	0-2%	K%
1988	62%	76%	81%	57%	19%	15%
1989	62%	75%	80%	57%	18%	15%
1990	62%	75%	81%	56%	18%	15%
1991	61%	75%	81%	56%	18%	15%
1992	62%	75%	81%	56%	19%	15%
1993	61%	75%	81%	56%	18%	15%
1994	61%	75%	80%	56%	19%	16%
1995	61%	74%	80%	56%	19%	16%
1996	61%	74%	80%	57%	19%	17%
1997	62%	74%	79%	57%	19%	17%
1998	62%	74%	79%	57%	19%	17%
1999	61%	74%	80%	56%	19%	16%
2000	61%	74%	80%	56%	20%	17%
2001	63%	73%	80%	59%	21%	17%
2002	62%	73%	80%	58%	21%	17%
2003	63%	73%	81%	59%	21%	16%
2004	62%	73%	80%	58%	21%	17%
2005	63%	73%	81%	59%	22%	16%
2006	63%	73%	80%	59%	22%	17%
2007	63%	73%	80%	59%	22%	17%
2008	63%	73%	80%	59%	22%	18%
2009	62%	72%	80%	58%	22%	18%
2010	63%	72%	79%	59%	23%	19%
2011	63%	72%	79%	59%	23%	19%
2012	63%	72%	78%	60%	24%	20%

We can probably go ahead and make this simpler to digest. Here, we break the years into groups of five, instead of proceeding individually.

Group	Strike%	AS/Str%	Contact%	1stStr%	0-2%	K%
1988-1992	62%	75%	81%	56%	18%	15%
1993-1997	61%	74%	80%	56%	19%	16%
1998-2002	62%	74%	80%	57%	20%	17%
2003-2007	63%	73%	80%	59%	22%	17%
2008-2012	63%	72%	79%	59%	23%	18%

Feel better? The final column is what we knew about — strikeouts have been going up, rather steadily. If you look at contact rate, there’s a small decline there over the past couple decades. But there’s also a lot more. On average, pitchers have been throwing slightly more strikes. However, hitters have been swinging less often at strikes, meaning there’s been an increased rate of strikes called. More and more plate appearances have started with a strike, and more and more plate appearances have reached an 0-and-2 count.

Obviously, a plate appearance that starts with a strike is more likely to lead to a strikeout than a plate appearance that starts with a ball (or a ball in play!). Obviously, a plate appearance that gets to 0-and-2 is more likely to lead to a strikeout than a plate appearance that doesn’t. Pitchers have generally been able to make hitters miss more often, but they’ve also gotten themselves into more favorable counts, and hitters have been a little more patient. There are those two effects — hitters have been taking more strikes, and when they’ve swung, they’ve missed a bit more.

Strikeouts have been going up, and we don’t know how much higher they might rise down the road. We have a good idea that a lot of this is due to harder throwers and the wisdom of sabermetrics. Everybody knows, now, that strikeouts are good for pitchers. Everybody knows, now, that strikeouts aren’t that bad for hitters. Of course these ideas have been showing up in the gameplay. But there’s more going on than big sluggers just sitting back and swinging hard. It isn’t just more swings and misses, and one should never underestimate the significance of a favorable count. In today’s analytical landscape, counts don’t get enough love.