A few days ago, don_jerovanni brought up the huge increase in walk rate the Royals have seen this spring training this season. At some point yesterday, the Royals were still walking at a 12.5% clip for spring training.
I looked at looked at the following stats to see if there was any correlation from the team's ST stats and the regular season:
- Batting Average
- OBP
- Extra Base Hits per Hit – I didn't know how to deal with the different park effects. I just wanted to see if there was any correlation with XBH from ST to regular season
- K/PA
- BB/PA
In all cases, PA was calculated using (AB + BB) because I was not able to find spring training stats with hit by pitch and sacrifice data.
Here are the results (all data is ST and regular season data from 1997 to 2008). The first line of values are the average change when subtracting the regular season value from the spring training value. For example, I took the 2008's spring training walk rate of 8.5% and subtracted the regular season value of 6.5% from it for a value of 1.9%. I also included the standard deviation in the values along with the r-squared values:
| Batting Average | OBP | Extra Base Hits per Hit | K/PA | BB/PA | |
| Average Difference | 0.027 | 0.031 | 1.8% | -0.7% | 0.9% |
| Standard Deviation | 0.016 | 0.018 | 2.6% | 1.6% | 0.9% |
| R-squared | 0.38 | 0.26 | 0.01 | 0.12 | 0.04 |
From the data, batting averages and OBP should be expected to dropped about 30 points for the team. Extra bases will also be down a bit. Strikeouts up and walks down.
A little deeper math here, so ignore if over your head. The r-squares are great with any of the data except AVG and OBP, those are relatively low. I think the key numbers to use would be standard deviation numbers. Take the team's values and then say they will probably be within 2 standard deviations. So with the walk rate this year, I would subtract 0.9% from it, for a value of 11.6%. Then the range would be 1.8% on both sides of it, or 9.8% to 14.2%. I expect the walk rate to continue to drop during ST, but it is an encouraging sign.
Regular season hitting stats are generally worse than spring training stats, but the level and certainty of the data available is not good enough to jump to any definite conclusions.
Source of spring training data: http://www.usatoday.com/sports/baseball/stats-archive.htm