One important way a manager can effect his team's performance is through bullpen management. A manager needs to bring in his relievers in the right situations, getting his best relievers in when the game is on the line. We can look at how Joe Torre is doing in this aspect of management using a stat called Leverage index. Leverage Index (LI) measures the importance of a game situation with a single number. According to Fangraphs Leverage Index is defined as:
"A measure of how important a particular situation is in a baseball game depending on the inning, score, outs, and number of players on base, created by Tom Tango."
The average LI is 1. This is the LI in a neutral game situation. In a blowout, the LI goes down because the situation is not as important. 60% of all game situations have a LI of less than 1. But if the score stays close, the LI goes up as you get into the later innings. 10% of all game situations have a LI of greater than 2. This is typically when a closer is used; the average closer has a LI of about 1.8 and the average set-up man about 1.3.
Obviously, you want to bring in your best relievers in the most important situations. Using gmLI (the average Leverage index when a pitcher enters a game) we can see how Dodger relievers are being used:
In general, Torre has done a good job making sure the best relievers get in the most important game situations. Jonathan Broxton, easily the best reliever on the team, also leads in gmLI by a comfortable margin. Cory Wade has been used in the second most important game situations, and while he has struggled, his FIP (Fielding Independent Pitching, defined here) suggests that is mostly due to bad luck. After him comes Hong-Chih Kuo, who was the set-up man early on because of his amazing performance in 2008. After that you have the effective combo of Ronald Belisario and Ramon Troncoso, who are coming in more important game situations as they gain Torre's trust. And at the bottom of the list there's Jeff Weaver, Scott Elbert, and Guillermo Mota, generally considered the worst pitchers on the Dodgers so far this year.