Wednesday, October 31, 2012

Lack of Speed Contributed to Inefficient Tigers Offense

Many Tigers fans grumbled that their team did not score enough runs given their hitting in 2012.  Simple statistics seem to back up their complaints: They were second in the American League in on-base percentage (.335) and fourth in slugging average (.422), but only sixth in runs scored (726).  

How many runs should the Tigers have scored? We can estimate the number of runs a team should have scored by the base runs (BsR) measure created by David Smythe in the early 1990s.  This metric is based on the idea that we can estimate team runs scored if we know the number of base runners, total bases, home runs and the typical score rate (the score rate is the percentage of base runners that score on average).

The basic base runs  formula includes at bats (AB), hits (H), total bases (TB), home runs (HR) and bases on balls (BB):

Base Runs = A*B/(B+C) + HR

A = baserunners = H + BB - HR
B = advancement = (1.4*TB - .6*H - 3*HR + .1*BB)
C = outs = AB - H
 

B/(B+C)= score rate


It's a complex formula, but it works quite well in estimating runs scored.  Table 1 below shows that the Tigers had 751 Base Runs in 2012.  That is how many runs a typical team with the same number of at bats, hits total bases, home runs and bases on balls as the Tigers would have been expected to score.  The Tigers scored 25 runs or 3.3% fewer runs than that.  This was the biggest under performance in the league.  


Table 1: AL Runs versus Base Runs, 2012


Team
R
BsR
R-BsR
% diff
Detroit
726
751
-25
-3.3
New York
804
823
-19
-2.3
Kansas City
676
687
-11
-1.7
Cleveland
667
675
-8
-1.3
Baltimore
712
713
-1
-0.1
Los Angeles
767
764
3
0.4
Texas
808
799
9
1.1
Minnesota
701
692
9
1.4
Oakland
713
696
17
2.5
Seattle
619
603
16
2.6
Tampa Bay
697
677
20
3.0
Boston
734
712
22
3.2
Chicago
748
722
26
3.7
Toronto
716
683
33
4.8
 Data Source: Baseball-Reference.com

So, what explains the 25-run discrepancy between Runs scored and Base Runs or expected runs? Some fans insisted that the Tigers did not hit well with runners in scoring position, but their league-leading .286 batting average with runners in scoring position belies that theory.  

Some also guessed that the Tigers lack of speed might have had something to do with their inability to score runs.  For example, they hit into a league-leading 156 double plays stole just 59 bases.  A more advanced Base Runs formula (found here) includes double plays, stolen bases, caught stealing, hit batsmen, sacrifice flies and divides walks into intentional and unintentional.  Table 2 shows that the Tigers should have scored 741 runs according to the advanced formula. Their runs scored total is closer to that figure, but still undershoots it by 15 or 2%.


Table 2: AL Runs Versus Advanced Base Runs, 2012


Team
R
BsR
R-BsR
% diff
New York
804
829
-25
-3.0
Kansas City
676
692
-16
-2.3
Detroit
726
741
-15
-2.0
Cleveland
667
677
-10
-1.4
Los Angeles
767
771
-4
-0.5
Oakland
713
711
2
0.3
Minnesota
701
696
5
0.7
Texas
808
801
7
0.8
Baltimore
712
705
7
1.0
Seattle
619
610
9
1.4
Tampa Bay
697
685
12
1.7
Boston
734
721
13
1.8
Chicago
748
735
13
1.8
Toronto
716
696
20
2.9

Data Source: Baseball-Reference.com

So, why do we still have a 15-run discrepancy?  The easy answer might be random variation or bad luck, but it's useful to explore further.  One possibility for the difference is that Detroit's lack of speed hurt them in other ways beyond double plays and stolen bases.  The Base Running Runs statistic at Baseball Prospectus suggests that they cost themselves about 12 runs with their failure to advance on ground balls and take the extra base on hits (e.g. going from first to third on a single).  That number seems to explain most of the remaining disparity in runs and expected runs.   

So, it appears that base running may have hurt the Tigers more than situational hitting in 2012.  Given that, it might be a good idea for them to add some team speed during the off-season. 

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