Best ‘Pen in the Bigs

Following a recent sweep by the Cubs at Wrigley Field, the White Sox last night got revenge by completing a sweep of their fellow Chicagoans on their own South Side turf. The 5-1 win gave the White Sox a 46-35 record and kept them in first place by 1.5 games over the Minnesota Twins. One of the key ingredients to their success this year has been the bullpen. Joe Morgan discussed how valuable they have been this year and the numbers back it up.

The White Sox bullpen currently has an MLB-best 2.61 ERA and has done so in 213.2 innings, a number lower than everyone except the Anaheim Los Angeles Californian Angels of Los Anaheim. The relief corps has not been called upon an exorbitant amount of time thanks in large part to the White Sox starting staff and their league leading 50 quality starts. That means in 62% of their games so far the bullpen hasn’t even gotten to rear its head until the seventh inning or later.

Overall, the White Sox have an MLB best 3.39 team ERA, and have walked just 227 batters—2.8 per game—which ranks second only to the Twins and their 198 free passes. Here are the five major components of the White Sox bullpen and their numbers:

Bobby Jenks: 32 G, 32.1 IP, 7 BB, 19 K, 1.95 ERA, 1.11 WHIP
Scott Linebrink: 36 G, 33.0 IP, 6 BB, 29 K, 1.36 ERA, 0.82 WHIP
Matt Thornton: 33 G, 31.1 IP, 9 BB, 40 K, 2.30 ERA, 0.80 WHIP
Boone Logan: 33 G, 28.1 IP, 6 BB, 29 K, 2.22 ERA, 1.09 WHIP
Octavio Dotel: 37 G, 36.2 IP, 19 BB, 53 K, 3.19 ERA, 1.36 WHIP

The games played numbers speak volumes toward the lack of overusage or abuse. In fact, you won’t find any White Sox relievers in the league leaders here on Fangraphs until you venture to the second page of players. Looking at all relievers with at least 20 IP—in order to get rid of those who wouldn’t qualify for relief rankings—the ChiSox have four in the top 35 in WHIP as well as three with K/BB ratios above 4.40; the other two chime in at a very respectable 2.79 and 2.71.

One aspect of bullpens I enjoy investigating involves how they were put together. With this team:

1. Bobby Jenks: selected off Waivers from Angels on 12/17/04
2. Scott Linebrink: signed 4 yr/19 mil deal this offseason
3. Matt Thornton: traded from Seattle for Joe Borchard on 3/20/06
4. Boone Logan: drafted 20th rd in 2002
5. Octavio Dotel: signed 2 yr/11 mil deal this offseason

Querying and exporting all relievers with 20+ innings allowed me to find some current averages. The average LOB rate for such relievers is 76.80%. Of the five White Sox discussed here, all but Dotel’s 71.7% come in at 78.5% or higher; Linebrink even sits at 92.1%.

In terms of WPA, the average for relievers with 20+ innings is 0.375. So, if we were to build a bullpen consisting of five “average” relievers (with 20+ IP), their WPA would amount to 1.88. Additionally, the average WPA/LI for this parameter is 0.282; five average pitchers with regards to this WPA/LI would combine for 1.41 context-neutral wins. The White Sox five currently have a 4.08 WPA and 3.48 WPA/LI, meaning they are 2.2 WPA wins above an average bullpen and 2.1 context-neutral wins above an average bullpen.

They have allowed the fourth least amount of total bases and have the second lowest OPS against at .687—only Oakland’s .661 ranks higher. Their bullpen may not sustain performance like this all season, but South Side fans should hope they do, considering their relievers have contributed the most win probability success to the team.