Fun Facts About Called Strikes

(Edited on 03/22/2015)
When reading the very good but complex recent article about pitch framing at Baseball Prospectus, I found myself wanting to step back and look more closely at the core of the measurement.  Before all the adjustments and the statistical modelling, it all starts with counting how many pitches are called for strikes as opposed to balls. 

So, I went to the retrosheet database for 2014 and analyzed all pitches that were called by umpires.  Any pitch that resulted in a swing was excluded.  There were 371,964 pitches called in Major League Baseball last year -  248,298 balls and 123,666 (or 33.2%) strikes.  The pitches are broken down by different splits such as home/away and ball/strike count in Table 1 below.  Here are some of the highlights:

• The pitching team was more like to get a called strike at home (33.5%) than on the road (33.0%).  Could this be a home field advantage?  We would need to look at it more closely, but it's certainly possible. 

• Not surprisingly, the most likely count in which to get a called strike was three balls and no strikes where pitchers know that most batters will be hesitant to swing (64.5%) were called strikes).  Conversely, only 8.3% of calls on no ball, two strike counts were strikes.

• There was a higher percentage of strikes called in the first inning (34.7%) than any other inning.  The percentage remained high for the first three innings, perhaps because starting pitchers are sharpest early in the game and the first time through the order.  The proportion dropped below average in the middle innings, but rose to 34.2% in the ninth inning when closers came into the game.

• Called strikes were more common with right-handed batters at the plate (33.5%) than left-handed batters (32.9%).  

•  Pitchers/catchers got more strike calls when their team was ahead (34.1%) versus behind (32.1%).  Of course, we need to consider that they may have had leads because they were throwing strikes rather than the other way around.   

•  More strikes were called when there were fewer outs - 34.8% with no outs, 32.8% with one out and 32.1 with two outs.

• Pitches were called strikes more frequently with the bases empty (35.3) than any other base runner situation. Strikes were only called 25.6% of the time with a runner on third.

Table 1 -Called Strike Splits -MLB Totals, 2014

Split	% Called Strikes
	(N=371,964)
Total	33.2
Site
Home	33.5
Away	33.0
Count
0-0	45.8
0-1	21.6
0-2	8.3
1-0	41.9
1-1	25.0
1-2	10.6
2-0	46.6
2-1	29.2
2-2	14.7
3-0	64.5
3-1	38.7
3-2	19.4
Inning
1	34.7
2	34.4
3	34.5
4	32.3
5	33.0
6	31.7
7	32.4
8	32.3
9	34.2
10+	31.8
Pitcher Hand
LHP	33.2
RHP	33.3
Batter Hand
LHB	32.9
RHB	33.5
Score
Behind	32.1
Tied	33.6
Ahead	34.1
Outs
0	34.8
1	32.8
2	32.1
Baserunners
Bases empty	35.3
1st	32.3
1st, 2nd	30.6
1st, 3rd	27.8
2nd	29.1
3rd	25.6
2nd, 3rd	25.9
1st, 2nd, 3rd	29.8

Data source: Retrosheet.org