Well, I had another column started, but I wasn't to enthusiastic about it, so when inspiration struck I quickly shifted gears to my new idea. Today there will be no long discussion on calculation of any new stats, but instead I'm going to focus on using some to answer questions I have about the Brewers defense this year and last. When it comes to defense we truly are in some of the last uncharted sabermetric waters. The most common stat, fielding percent gives very little insight into a true defensive ability. Other stats such as zone rating (ZR) and range factor (RF) have limitations due for a variety of reasons though they are more informative than fielding percentage. The widely used personal observation is only slightly better than errors in terms of value as an example see Derek Jeter. At this point in time our best hope is to use all of the available tools with full knowledge of their weaknesses in the hopes of building as complete a defensive picture as possible.
One of the newest revolutions in analyzing defense is the idea of defensive efficiency. Thanks to Voros M. others have used his research as a handy way to assess team defense. The idea is simple if pitchers don't influence the rate of hits on balls in play the defense is responsible for all the variation you see in that measure (assuming that over the course of a season every team sees roughly the same level off hitters). Team defense can be summed up quite quickly by finding the percentage of balls in play that go for hits. Certainly this doesn't represent every facet of team defense, as CS, OF assists, cutting off balls in the gap also have importance not measured. Still in my mind this is one of the best ideas in defensive evaluation.
So what was my original question? I wanted to know to what extent defensive changes had affected our pitching staffs numbers. To this point in the season essentially 2 changes have been made from last year. EY replaced Belliard at second and Alex Sanchez has taken the playing time that went to Devon White last year. It stands to reason then that any changes that appear are likely to be a result of those changes. So have there been any changes? Looking at the first table that shows BIP (Ball in play), DE (defensive efficiency the rate at which BIP become hits), and ground ball to fly ball ratio. As you can see there has been a noticeable increase in that at which hits are falling in for the team. But what does that mean in a tangible sense how many hits is that? To this point in the season the defense has allowed 4 more hits than it would have allowed last year on the same number of BIP. That hardly seems very significant at most a couple of runs?
Well I think it's worth taking a look at some other team trends. In the second set of columns are some of the numbers needed to calculate BIP, but the more interesting numbers are the comparisons of K/I and I/HR. The pitching staff has increased it's K rate to the point that they've struck out 11 more men then they would have last season, which actually would have the affect of preventing about 3 more hits. Looking at the BB numbers there's more improvement with the pitchers walking fewer batters prorated from last season there've been about 5 fewer than last year. On balance then it would seem like the pitching staff should have made an incremental improvement even with the defense being a bit worse. Except there's one important number remaining, I/HR. Here the pitchers have been much worse this year to the point that they've allowed 6 more HRs than last year at this time. That's at least 6 more runs right there and 10 is probably a more accurate number, that clearly cancels out the incremental improvement in BB/K numbers.
Getting back to the defense though I mentioned CF and second base as areas of major change, and I was wondering if either was primarily responsible for the change in defense. Looking first at table 3 we compare Belliard and EY side by side as the primary second basemen TC is total chances and DP is double plays. For the moment focusing on the last 3 columns range factor, zone rating and fielding percentage it would seem that Belly is better hands down, which fits with our perceptions, but one of EY's biggest criticisms has always been turning the double play. I'm not sure if it's a very accurate measure, but based on the rate of total chances each player received Belly would have only 1 more double play so far this year and using the ZR numbers Belly would have 2 more outs. Unfortunately there's more complicated things going on behind these numbers, so some of my conclusions could be flawed especially looking at range factor it would certainly seem that the difference here would indicate that more balls were hit to second base last year than this year, which is an interesting trend, supported in part by the slight decrease in the G/F ratio and the increase in HR.
Looking at CF (table 4) we see that Jeffery Hammonds numbers are down quite a bit defensively with big drop offs in ZR and RF, some of this drop off is likely due to small sampling with Jeffery not having that many innings in either year. The interesting comparison though is Sanchez to White. Sanchez has a much higher RF this year, but a much lower ZR than White. After puzzling over this I concluded that the most likely explanation was that more balls were being hit to Alex this year than White, but Alex was not doing so well at getting to all of them. This kind of fits a general theme with more fly balls being hit particularly up the middle taking chances from second to CF. Based on this I can say that EY has had little defensive impact based mostly on a change in pitching patterns, and most of the change in defense is a result of Sanchez being a mediocre defender.
||BIP (I*3 +H - HR-K)
TABLE 3 (2B)
TABLE 4 (CF)
PLAYER OF THE WEEK
Unlike last week there were no clear candidates. Tyler still managed to have a pretty good week, but he tailed off and I'm inclined to look elsewhere before giving a player 2 in a row. My second candidate emerged out of obscurity to have a pretty good week. Mark Loretta in only 11 ABs hit 3 doubles and took 3 walks to raise his OPS well over .100 points, and stake a claim to actually taking playing time away from EY. But neither was my choice, that honor goes to Glendon Rusch for 2 consecutive starts without allowing a run and garnering two wins. Included of course was the complete game shutout to give him 3 complete games on the year. Anytime a player prevents Royster from abusing a bullpen arm it's a good thing even if the timing effectively gave the relievers another All-star break.