Effective today, we have begun to list the league leaders in the four QUAD categories and the top three in strikeouts per 100 pitches at the bottom of our sidebar. These stats will be updated every Sunday morning (through games of the day before).

As a reminder, the QUAD encompasses the four most important offensive categories: on-base percentage (OBP), slugging average (SLG), times on base (TOB), and total bases (TB). The first two measures are rate stats and the latter two are counting stats. Players who lead their respective leagues in both rate and counting stats--such as Albert Pujols--are clearly the most productive hitters in the game.

Pujols is leading the NL in SLG (.925), TOB (52), and TB (74). Jason Giambi sits atop the AL in OBP (.557) and SLG (.828). The 2005 NL MVP led the league in TOB last year, while placing second in OBP, SLG, and TB. The 2000 AL MVP led his league in OBP last season, while finishing eighth in SLG. (See the 2005 top ten leaders in all four categories for both leagues here.)

The strikeouts per 100 pitches (K/100P) stat is more highly correlated to run prevention than strikeouts per nine innings (K/9) or strikeouts per batter faced (K/BF). It measures pitching proficiency as well as any stat using just one variable in the numerator and one variable (such as innings, batters faced, or pitches) in the denominator.

Ben Sheets is showing just how valuable he is to the Milwaukee Brewers, leading the majors in K/100P with 8.77. Johan Santana led MLB in 2005 with 7.14 (among those with 162 or more IP). Activated from the DL on April 16, Sheets has started three games, throwing 18 innings while striking out 25 batters against just one walk. His 1-2 W-L record and 4.00 ERA do not reflect how well he has pitched in the early going.

Cory Lidle is probably the biggest surprise among the league leaders. The Philadelphia right-hander has whiffed 33 batters in 30 2/3 IP and is averaging 7.48 K/100P. He has the lowest number of pitches per plate appearance (3.47) and pitches per inning (14.4) among the strikeout leaders, primarily owing to the fact that he has only walked three batters thus far. Lidle is first in K/BB at 11.00. The only stat failing him is batting average on balls in play (.344). If Cory continues to pitch as well as he has in his first five starts, look for his BABIP to regress toward the league average--usually around .300--and his ERA (4.40) to decline accordingly.

Seeing J.J. Putz leading the AL might also open up some eyes. The Seattle relief pitcher has struck out 21 batters in 14 innings and is averaging 8.57 K/100P. Other than 2001 when pitching for San Antonio in Double-A, Putz has never had 7 Ks per 9 IP in his minor or major league career. J.J.'s groundball-to-flyball ratio (G/F) of 2.38 is also intriguing. Keep an eye on the 29-year-old Mariner as a pitcher who may be on the verge of a breakout season.

Be sure to check back on Sundays for ongoing updates throughout the season.