Something in the water in Chi-town?

The Cubs and Sox in Chicago scored a combined 25 runs yesterday. But, as we’ll see in a moment, that was atypical of this year’s Chicago teams. (And they only won one of the two games.)

We’re about a quarter of the way through the season and offense is up in baseball overall. Last year Major League Baseball teams averaged 4.65 runs per game. We haven’t even reached the homer-friendly summer months, and teams are already averaging 4.80 runs per game in 2009. That may not seem like a big change, but it comes out to 738 more runs over the course of a full season, or about 25 additional runs per team.

Despite the fact that offense is up, the two Chicago clubs have started the season well below last year’s pace. The White Sox have seen the biggest drop-off, going from 4.98 runs per game last year to 4.18 this year. If they don’t turn things around, the Sox will score 134 fewer runs than last year’s AL Central champions. Similarly, the Cubs have gone from 5.31 runs per game in 2008 to 4.53 this season. Neither team is vastly different from last year’s version, but both have multiple hitters off to slow starts in 2009.

The Sox and Cubs are both on pace to finish with well over 100 runs less than last year. No other team is close. The next worst projected drop-off is 69 runs by the Seattle Mariners.

On the flip side of the coin, the Los Angeles Dodgers have a vastly improved offense, scoring 1.35 runs per game more than the 2008 Dodgers. Over a full season, this adds up to more than an additional 200 runs. Late last year the Dodgers added two potent bats, Casey Blake and Manny Ramirez; both were re-signed last offseason and have paid huge dividends. The 2008 AL Champion Rays have also improved substantially, thanks to strong starts from Evan Longoria, Carlos Pena, Jason Bartlett, and Ben Zobrist.

Here are the biggest dropoffs and improvements from 2008 to 2009: