Run Preventing Events - 2007

Today, I’ll continue with the batted balls versus pitchers theme which I started earlier this week. An at bat can result in any of the following events:

• Strikeout
• Base on balls
• Hits batsman
• Ground ball
• Line drive
• Outfield fly
• Infield fly

Three of those events are generally favorable events for pitchers:

• Strikeout
• Ground ball
• Infield fly

I call these run preventing events (RPE). Of course, a ground ball is not as easy an out as a strikeout or an infield fly and can have a negative result for a pitcher. However, inducing a lot of ground balls will help to prevent runs over the course of a season. On the other hand, it is good for pitchers to avoid, for the most part, the following events:

• Base on balls
• Hits batsman
• Line drive
• Outfield fly

Last year, I created a statistic I call Run Preventing Event percentage (RPE%) which is calculated as follows: (SO + GB + IFF)/BFP. Striking out batters and inducing grounders have been shown to be repeatable skills. Getting batters to hit infield flies is not stable from year to year (correlation = .10 between 2005 and 20065). However, infield flies are relatively rare compared to other batted ball types and including them does not change the RPE% substantially in most cases. Plus, I suspect (without statistical evidence) that this is a real ability for some power pitchers.

It turns out that RPE% is fairly stable with a .66 correlation between 2005 and 2006. It can also be considered a fielding independent stat because, although the end result is not independent of fielders, getting a grounder or infield fly to happen in the first place has nothing to do with fielders. It is as stable or more stable than FIP ERA but it is not weighted and thus does not explain as much about runs allowed. Part of the value of RPE% is its simplicity.

There were 65 American League starters with 17 or more starts in 2007. Table 1 lists the RPE% rankings for Tigers starters. Table 2 lists the top 20 pitchers in the league. In general, the RPE% seems to be good for identifying effective pitchers but it gives rather unusual results for a couple of Tiger starters: Jeremy Bonderman and Justin Verlander.

From the tables, we can see that Bonderman (RPE%=57.2) ranked very well (9^th in the AL) and was the only Tigers pitcher in the top 20 in 2007. I mentioned in the starting pitcher FIP ERA article, Bonderman does well on fielding independent stats (strike outs, walks, ground balls) but allows runs in bunches, particularly in the first inning. His problems with runners on base are illustrated by his OPS against splits: .827 with runners on base, .888 with runners in scoring position and .748 with the bases empty.

In contrast to Bonderman, Verlander had an RPE% (52.1) which was close to league average. Verlander had a lower than average ground ball percentage (41%) but had very good results on fly balls and line drives. According to The Hardball Times Baseball Annual 2008, he allowed fewer runs per line drive(.32) than any American League pitcher. He also finished in the top 5 in runs per outfield fly (.14). This may be an indication that he did not allow well hit balls when runners were on base.

The other three pitchers expected to start for the Tigers in 2008, had RPE percentages of league average or just below: Kenny Rogers 52.0, Dontrelle Willis (51.5), and Nate Robertson (51.1).

The raw data used in calculating RPE% were abstracted from The Hardball Times database.


Table 1: Run Preventing Events for Tigers Starters in 2007

Rank	Name	IP	SO	GB	IF	RPE	RPE%
9	Bonderman	174.3	145	266	20	431	57.2
31	Verlander	201.7	183	245	23	451	52.1
34	Willis	205.3	146	322	17	485	51.5
41	Robertson	177.7	119	266	14	399	51.1
50	Durbin	127.7	66	193	17	276	49.2
.	Jurrjens	30.7	13	37	6	56	45.9
.	Maroth	78.3	28	120	9	157	45.4
.	Miller	64.0	56	102	7	165	53.4
.	Rogers	63.0	36	102	5	143	52.0

Table 2: Top 20 AL Starters by RPE% in 2007

Rank	Name	Team	IP	SO	GB	IF	RPE	RPE%
1	Hernandez	SEA	190.3	165	357	11	533	66.0
2	Carmona	CLE	215.0	137	431	8	576	65.5
3	Burnett	TOR	165.7	176	239	15	430	62.2
4	Bedard	BAL	182.0	221	216	12	449	61.3
5	Beckett	BOS	200.7	194	276	29	499	60.7
6	Wang	NYA	199.3	104	381	12	497	60.4
7	McGowan	TOR	169.7	144	264	10	418	59.3
8	Halladay	TOR	225.3	139	391	19	549	59.2
9	Bonderman	DET	174.3	145	266	20	431	57.2
10	Sabathia	CLE	241.0	209	324	25	558	57.2
11	Loe	TEX	136.0	78	269	3	350	56.9
12	DiNardo	OAK	131.3	59	249	7	315	56.8
13	Kazmir	TB	206.7	239	238	23	500	56.4
14	Westbrook	CLE	152.0	93	264	7	364	56.2
15	Haren	OAK	222.7	192	304	28	524	56.0
16	Shields	TB	215.0	184	279	25	488	55.8
17	Tavarez	BOS	134.7	77	252	8	337	55.8
18	Meche	KC	216.0	156	321	26	503	55.5
19	Gaudin	OAK	199.3	154	318	18	490	55.3
20	Blanton	OAK	230.0	140	359	26	525	55.3