The Major League Baseball All-Star break is this week, so it’s a good time to step back and review the key statistics to identify the most productive players and teams over the first half of the season.

Following on my latest periodic post on the Stros, regular readers of this blog know that RCAA ("runs created against average") and RSAA ("runs saved against average") statistics, developed by Lee Sinins for his Sabermetric Baseball Encyclopedia, provide a simple but revealing benchmark of how an MLB player or MLB team is performing during the long MLB season.

RCAA reflects how many more (or fewer) runs that player generate relative to a league-average player (an exactly league-average player’s RCAA is zero).

Similarly, RSAA measures how many more (or fewer) runs that a pitcher saves relative to a league-average pitcher (an exactly league-average pitcher RSAA is zero).

Thus, a club’s positive RCAA number reflects how many more runs a club’s hitters are generating relative to what a league-average club would generate using the same number of outs. Likewise, a club’s positive RSAA number reflects how many more runs the club’s pitching staff is saving relative to what a league-average pitching staff would prevent in the same number of innings. Negative RCAA and RSAA numbers are just the opposite. A negative RCAA reflects how many fewer runs a club’s hitters are generating relative to a league-average club and a negative RSAA indicates how many more runs a pitching staff is giving up in comparison to a league-average staff.

Accordingly, focusing on those two basic statistics, let’s review the top players and the top teams from the first half of the 2009 season:

The top 20 hitters in RCAA in the National League:

The top 20 hitters in RCAA from the American League:

Yes, that no. 2 in AL RCAA is the same Ben Zobrist who was a throw-in by the Stros in the Dan Wheeler-for-Aubrey Huff trade with the Rays a couple of years ago. And former Stros OF Luke Scott (T 7th) would be more productive, a whole lot cheaper and much better defensively than the Stros LF, Carlos Lee. Ouch!

The top 10 pitchers in RSAA from the National League:

And the top 10 pitchers in RSAA from the American League:

The following is how the National League teams stack up in terms of RCAA:

And here is the National League teams’ rankings in terms of RSAA:

Note that the Dodgers are the only NL club with a well above-average RCAA and RSAA number. Every other club is mediocre or poor in either RCAA or RSAA, or both.

Here is how the American League teams rank in RCAA:

And the American League teams’ RSAA rankings:

The AL East has three of MLB’s strongest teams in the Yankees, Red Sox and Rays. And the Blue Jays are pretty decent, too!

Here are the Stros hitters’ individual RCAA ranking:

And the Stros pitchers’ RSAA:

The following chart shows the NL Central clubs’ net RCAA/RSAA figure, along with the current percentage chance of making the playoffs, as calculated by Coolstandings.com.

National League Central

And finally, the following chart shows the Stros’ net RCAA/RSAA figures and corresponding won/loss record for each season since the 2000 season. Note that the Stros’ only losing seasons were in seasons in which the pitching staff fell apart (large negative RSAA in 2000 and 2007) and the club’s most successful season was when the pitching staff was dominant (2005). Also, note how the club’s deterioration since 2006 coincides with a substantial decline in the Stros’ generally productive pitching staffs from earlier in the decade:

The bottom line — although a considerably better hitting club than last season’s poor-hitting outfit, and despite the fact that the Stros have been arguably the luckiest team in MLB so far this season, the club’s combination of barely above-average hitting and below-average pitching will struggle to equal last season’s record. A break even mark or somewhat below break even is more likely.