Offense is 2007 continues to lag behind offense in 2006. Over the last week, the gap started to widen again. Right now, total runs per game is about 0.7 runs lower than through he same point last year. Here’s a graph of each individual day over the two seasons (click on graph for a full size view):
As you can see, most of the difference resulted from low scoring early in the season, giving credence to the weather explanation. At the end of April (around Day 27) things start to even out, and 2007 looks a lot like 2006. But lately scoring diverged again. The weather’s been nice in the northeast lately, but I know a lot of rain fell on other parts of the country. Unfortunately, I don’t have weather data, so I’ll leave that to other researchers.
Note, also, that in 2006 up to this point there were twelve days in which the league averaged eleven runs per game or better, and only one this season. In contrast, six games in 2007 fell at or below seven runs per game, while there was just one in 2006.
Also note that early in the season you can pick out the days the #1 starters pitched, and the days the #5 starters pitched. After two weeks, these get jumbled enough that the volatility in runs per game goes down. Which is another reason the recent week of 2007 is interesting, the volatility went back up.
I’m not totally convinced the weather is the only factor at work here. The weather is improving, but runs per game are starting to get worse again. The current blip down is too short a time frame to be meaningful, but it bears watching.
There seems to be a lot more good young pitchers entering the Majors than in years past. This lower scoring trend will continue. I think it explains the scoring diffential between last year and this, but it does not explain how huge the differential is. What does explain it? Luck and a small sample size (only two months of one season).
Significant YTY increase or decrease in offensive totals can only be attributed to the balls used or a changing strike zone, in in war time due to a drastic reduction in the talent pool. If the numbers hold up for the entire year, my bet is the ball has lost a bit of the juice which may have spawned the juiced era. MLB has had to explain why their steroid policy is not showing any reductions in offense since it was implemented, deadening the ball is one solution to quieting the critics.
The balls would still be within major league specs, the specs are so broad that the difference between a ball meeting the specs at the low end and one meeting the specs at the high end, is a theoretical difference of +/- 25 ft in a ball that is hit 400 ft at the median of the specs. (this from the MLB report on balls tested from 1999 and 2000)
It could also mean that effects of players going off steroids are taking effect now as well, but to believe that you have to believe the sudden offensive jumps from 1993/19994 were due only to steroids.