Bullpen Report on All 10 Teams

Note: All statistics in the table below are from games up to and including May 13.

Which team in either the AL or NL West has the best bullpen this season?


There is no other place to start. Already we learn some things: the Astros bullpen is almost definitely bad and the opposite can be said for the Padres and Giants. Things are harder to judge for the other seven teams. Generally speaking, you’d expect lower ERAs in the NL (blue text) compared to the AL (red). The A’s ERA looks especially impressive in that light–at least as impressive as the ERAs for the Giants and Padres. But they have seven losses reflecting seven instances of failure, an average number for this lot.


Looking at raw numbers of runs and earned runs allowed clarifies the imbalance between the Astros and Padres. The difference between the two bullpens is 52 earned runs. That makes up for most of the 65-run difference between the two pitching staffs entire. In other words, the Astros starting rotation has been only 13 earned runs worse than the Padres starting rotation. The two teams are on opposite ends of the league when it comes to run prevention–the Astros are a laughingstock and the Padres perennially impressive–and 80 percent of the difference can be traced to the bullpen. If they weren’t already losing, the Astros would lose a lot games late, to the tune of oh so many home runs.


Here we see that the Dodgers and Diamondbacks relief pitchers have worked the most. This circumstance has probably been to the detriment of Los Angeles, but for Arizona it’s not so bad. A .300 OBP can be either Raul IbaƱez or Alcides Escobar, depending on the power that comes with it. Diamondbacks relievers have given up a lot of home runs, but that’s a thing that often evens out over time. Addison Reed has given up 6 home runs by himself. This season it doesn’t matter much, but he was acquired to be the closer for at least few years. That trade must look worse to Diamondbacks fans each day.


Saves and holds are rather archaic, but with each one of these bright tables we add a little bit of nuance to our understanding. Here the Rockies come off poorly, whereas they were previously doddering around the middle of the tables for ERA, runs and OBP. Fun fact: all nine of their saves came from LaTroy Hawkins, and he hasn’t blown any saves yet. The eight blown saves come courtesy of Rex Brothers (4), Boone Logan (2), Matt Belisle and Adam Ottavino (1 each).

This table makes a case for the Mariners having the best bullpen in the division. Oakland’s closing carousel has given most everyone a chance to blow some saves, but no one has seized the opportunity like Luke Gregorson (4). Even so, his ERA (2.37) remains stubbornly below that of his chief competitors, Sean Doolittle (3.60) and Jim Johnson (4.96).


Limiting walks is the fundamental and defining aspect of the Giants bullpen, the reason for their success. On May 13 only one man in their bullpen had more than five walks: Santiago Casilla, with seven. Conversely, the Dodgers had one reliever with five walks, and that was Brandon League. Everyone else had at least eight walks; Chris Withrow had 15. The problem seems be an endemic one for the Dodgers, and it should be tough to fix.


After all, you can see they throw it into the zone less than any other team. The Mariners and Angels are right behind them–this whole table lines up with our expectations.


The Giants and Padres are the best at getting hitters to chase at pitches outside the strikezone. Their excellent performance thus far is founded in real skills, though we shouldn’t expect the Giants to hold an advantage of nearly four percent. National League hitters seem more prone to swing outside the zone. Perhaps this is because once relievers are pitching for one team, they are probably pitching for the other team as well, which means their spots in the lineup go to bench players, who are generally worse hitters than starters. So relievers in the NL face bench players regularly, while relievers in the AL simply face the starting lineup.


I should have sorted by K%. Sorry. The Diamondbacks and Angels have bullpens that lead their respective division in strikeout percentage, for all the good that has done them. This honestly doesn’t seem to have all that much bearing on success. At least, it’s not a fundamental aspect of anyone’s success. Of course, the Astros are worst at it, which must mean something.


I think to think O-Swing percentage is a good proxy for walks (as demonstrated above), and I think the same way about Swinging Strike percentage and strikeouts. Furthermore, SwStr% (or Whiff%) is a good proxy for stuff. Better stuff, more whiffs–you don’t need to be smart to understand baseball, that’s the best part.

So do the Rangers have the worst collective bullpen stuff? Hard to believe with their recent history and the existence of a player named the Mexicutioner on their staff, but it’s possible. Injuries have struck more often than plague; more than 11 pitchers have thrown five innings. Bodies out of Triple-A or off the waiver wire will not be able to blow away major league hitters. And pitchers are going to the DL faster than they are returning. Texas needs bullpen help before the deadline. That they lag in Whiff% is a reflection of how thin their talent has been stretched by injury.


Even so, the Rangers have a good enough defense, and all the Balls In Play are in good hands. Same goes for the Rockies and the Dodgers. Unifying link between all three teams: an excellent defensive shortstop. Brandon Crawford for the Giants, Troy Tulowitzki for the Rockies and Elvis Andrus for the Rangers make it easier for their teams to target groundball pitchers. There are no better defensive shortstops in these divisions. Now let’s see what kinds of Balls In Play these bullpens have ceded.


Welp. Turns out the Rangers don’t care about groundballs enough to maximize them. They do have three good defenders in the outfield, however. The Giants are crazy for grounders, though, and rightfully so. Crawford is not alone on that infield in terms of leather superiority. Pablo Sandoval is a reliable gloveman with a rocket arm and quick instincts. Brandon Belt is out for a while but only his left thumb is injured; he could still go out there and scoop one-hoppers with aplomb–and few have a longer stretch than the Baby Giraffe. Brandon Hicks is batting .200 or so and he’s still the interim second baseman, his glove is no brick.

The A’s are really into hitting flyballs so it makes sense that they would assemble pitchers to do the opposite. If, as an organization, you’ve found an offensive strategy you like, you don’t want your pitchers playing into that strategy for other teams.


The Angels say: let them hit it in the air and let Mike Trout bring it unto his glove. That’s what the fans want damn it. Meanwhile, Colorado knows better than to let the ball get in the Rocky Mountain air. It’s the only way to hold a lead in Coors Field.


Yeeesh, Mariners! Nobody looks at the Astros pitching and says, “I want that, but more line drives,” unless they are literally going insane in that very moment. Oddly, the chief culprit are Tom Wilhelmsen, Fernando Rodney and Charlie “A Bird in the Hand, a Hand in the” Furbush. Wilhemsen and Rodney are their two best right-handers, and their performance has not suffered for all the hard hits they allow.

The Giants have a preposterously low line-drive rate and a preposterously high groundball rate. Those facts in tandem should give us pause. For them to continue all season is impractical. No other team’s bullpen, in all the majors, has a GB/FB ratio over two. Right now their bullpen is neck and neck with San Diego’s but San Diego has a stronger case going forward. Shit, the Padres probably have the best bullpen in the league, so they get their own post, later.

These last two graphs are presented without comment. Pitches per Plate Appearance is what P/PA stands for. Pace means how many seconds between pitches.



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