Team Bullpens

Some teams have great starters, some have great bullpens. Some have both, some have neither. Which is my way of introducing this graph of the 2004 ERA for each team’s starters and relievers:

Overall, starters had a 4.65 ERA vs. a 4.19 ERA for relievers. I present this for informational purposes only — not to imply that relievers are better than starters. Consistently pitching 150 to 200 innings well is harder than consistently pitching 50 to 100 innings well. Really, the point of the graph is to stress the relative contribution each team got from its starters vs. its relievers. Along the same lines, it’s also important to note that these numbers are not corrected for home parks. Such as the Texas Rangers’ Ballpark at Arlington.

Because of their hitter-friendly park, the nature of the Rangers’ 2004 season is sometimes misunderstood. But the Rangers had some of the best pitching in the majors last year. In the American League, the Rangers trailed only the Twins and A’s in total defensive (fielding and pitching) Win Shares. And as the above graph illustrates, the guys in the bullpen were key to their success. In fact, the Dodgers, Angels, Cardinals and Rangers may have had the best bullpens in the majors last year. Hmm. Let’s see if we can figure out if that’s true.

Over at Baseball Prospectus, they keep track of something called Win Expectancy Added for every major league reliever, which I assume is based on the same principle as Win Probability (covered in a previous article). Win Probability/Expectancy Added is a great way to evaluate relievers, because it measures their impact on the game (which is what relievers are really paid to do) by looking at how well they pitch AND how critical their appearances are during the game. But Baseball Prospectus doesn’t add up their Reliever’s Win Expectancy Added by team, so I decided to take a crack at it.

Ta da! Following are the official THT bullpen rankings, based on our own analysis of each bullpen’s “Win Probability Added” (WPA). The following numbers represent the number of wins above/below 81 that each bullpen contributed to its team’s record. These rankings are not adjusted for ballpark, which means they will overrate teams like the Padres and Dodgers, and underrate teams like the Rockies and Diamondbacks. For more details regarding the methodology, please see our footnote below.

American League                 National League

Team          WPA               Team        WPA
-----         ----              -----       ----
ANA           6.09              LAD         6.86
NYY           4.09              STL         5.81
MIN           3.88              PHI         5.59
BOS           3.59              ATL         4.05
TEX           3.53              SDP         2.79
BAL           2.58              HOU         2.44
TBD           0.33              CHC         1.53
OAK          -1.97              NYM        -0.21
CLE          -3.09              MIL        -0.98
SEA          -4.38              MON        -1.89
CHW          -4.49              FLO        -1.92
DET          -4.70              PIT        -2.08
TOR          -7.34              CIN        -3.10
KC           -9.09              ARI        -5.80
                                SFG        -6.80
                                COL        -8.98

Remember that Bullpen WPA is a complicated calculation — it reflects how well a pitcher pitched at a certain point in a certain game, added up over a season. What I’m really saying is that I can’t explain why some of these teams rank where they do. Hey, this is new for me too. But here are a few observations:

• The Dodgers had a great record (43-29) in one- and two-run games. It appears that much of the credit for that record goes to Mr. Gagne and friends.
• Conversely, the Yankees also had a great record in close games (50-24) but the bullpen appears to be only partly responsible for that record. Apparently, more of the credit should probably go to their batters, who batted .867 (OPS) in close and late situations.
• I, for one, didn’t realize how good the Philly bullpen was last year. Billy Wagner, Tim Worrell, Ryan Madson and Amaury Telemaco all contributed more than one win each.
• The Rangers rank relatively low on this list but, as I said, I wasn’t able to run a ballpark adjustment on the data. My best guess at this point is that a ballpark adjustment would raise their WPA to about 4.2, behind only the Angels in the AL. This is a tremendous turnaround from two years ago, when the Ranger bullpen compiled the worst WPA of the past three years (-12.42).

Win Probability is a great stat but, like Win Shares, it’s not necessarily an indication of “true talent,” and it’s not necessarily a predictable stat. So let’s finish by presenting each team’s bullpen :FIP:, a far more predictable stat, to take a peek at how these bullpens might perform next year.

American League                 National League

Team           FIP              Team         FIP
-----         ----              -----       ----
ANA           3.44              STL         3.62
MIN           3.75              LAD         3.68
TEX           3.94              NYM         3.98
NYY           4.04              PIT         4.03
BOS           4.12              ATL         4.09
BAL           4.14              HOU         4.18
TBD           4.36              SDP         4.19
OAK           4.43              PHI         4.19
KC            4.49              CHC         4.22
CLE           4.55              MIL         4.37
SEA           4.66              FLO         4.48
TOR           4.67              MON         4.52
CHW           4.71              SFG         4.74
DET           4.92              ARI         4.93
                                COL         4.99
                                CIN         5.20

On the surface, it would appear that the Texas bullpen can do it again, but that Philly performance may have been a bit of a fluke. The Mets’ bullpen might contribute more next year as well. And wasn’t the Angel bullpen awesome?

How many days until Spring Training?

References & Resources
Here’s how I computed Bullpen WPA:

• I calculated the Win Probability of the game at every point at which a reliever entered a game. This was based on the score, inning, number of outs and base situation.
• I then calculated the Win Probability of the point at which the reliever left the game, based on the same factors AS WELL AS the number of runs an average team would have scored during his time in the game.
• The difference between the two Win Probabilities equals Win Probability Added for that appearance. I then added up all Win Probabilities Added for all relievers for the team totals.

For average runs the team would have scored, I used 0.5 runs per inning, or 4.5 runs a game. This overall average probably negatively impacts the Bullpen WPA of all American League teams, as well as teams in hitter’s parks. It positively impacts teams in the National League, and teams in pitcher’s parks.

Despite these caveats, I think this is a relatively good measure of bullpen effectiveness.

I should also mention that this is not exactly the same methodology that Doug Drinen used for his “Win Probability Added”, which was published in the Big, Bad Baseball Annual. Thanks to Doug for letting us use the WPA title, and also to Tangotiger for his always-generous advice.

Please note that this article is not meant to be an exhaustive study of team bullpens.