Riggleman's Pitch Counts

This study was half-finished a few days ago, but then I went to a conference. I hadn't even planned to do more work with the starting pitching, intending to look at another facet of the Nationals' spring training questions instead. But Mr Riggleman brought up suspicions some of us have had about whether he puts too much stress on his pitchers' arms.

To make a stab at seeing whether Mr Riggleman has adopted a new approach, I used Baseball Reference to assemble game-by-game data for all the starters used during Mr Riggleman's tenure. They included three starters used by Manny Acta, so looking at them together, we might get a sense of it all.

The study found the average pitch counts, the standard deviation of these and, based on the standard deviation, an anticipated maximum number of pitches per start, the number of outings and the number of times the anticipated maxium was exceeded. I also added in the average percent of Win Probability Added, to see whether more successful pitchers were kept on a longer pitch-count leash; and age, to see if older pitchers were allowed to go deeper.

Under Manny Acta:

Pitcher    Age   AvgPC   PCStDev     Max    Out    Max+    WPA%
Lannan       24    95      11.7      107    17      2        4
Stammen      25    88       9.6       98    10      1       -8
Detwiler     23    88      10.7       99    10      1      -12

Under Mr Riggleman:

Pitcher    Age   AvgPC   PCStDev     Max    Out    Max+     WPA%
Lannan       24    94      19.4      113    16      2       -1
Stammen      25    77      20.5       98     9      0      -10
Detwiler     23    75      25.2      100     5      0       12
Mock         26    93      12.4      105    15      3      -11
Martin       26    86      19.5      106    15      0       -3
Balester     23    73      15.7       89     7      1      -13
Livan        34    98      10.5      109     8      1       -8

This isn't quite what I expected to see. The big difference between Riggleman and Acta is not pitch counts (although there is a difference), but whether or not to leave a pitcher in. Acta appears to have quite a strict 'pitch count' mentality, setting a target for a pitcher and pulling him quite quickly once the target is reached, thus being a relatively 'slow hook'. Riggleman, by contrast, was more mercurial in the sense that he might pull a pitcher very quickly (Martin, 25 July, 28 pitches!) or leave them in for a very long time (Lannan, 25 September, 122 pitches!). This isn't in the table, but based on Win Probability, pitchers under both these men were more likely to run up maximum-busting totals if they were not pitching well.

I'd say Mr Riggleman, relative to Manny Acta, is a quick hook. I'm also not convinced that he's learned as much as he thinks.