Relief Corps Controllable Skills
The goal of an ideal bullpen is to relieve the starting pitcher and effectively shut the opposition down to the point that they stand no chance of coming back. We hear so often the idea that playoff spots are won and lost in the bullpen, and from reading numerous blogs, one might think that 26 of the 30 major league teams have “the worst bullpen in baseball.” In my eyes, the best type of reliever is one who limits his walks, gives up as few home runs as possible, and strikes out as many batters as he can. These are the controllable skills for a pitcher, or, in other words, game outcomes that have nothing to do with the defense. Which bullpen comes closest to this ideal reliever? Well, with the update to the team pages here at Fangraphs, we now have the capability to check.
For starters, which relief corps posted the best strikeout rates? The Cubs (8.68), Yankees (8.66), and Dodgers (8.62) vastly stood out from the rest in this category. The impressive Rays bullpen came in fourth place at 8.03, narrowly ahead of the Reds at 7.97. At the bottom of the league were the Pirates (6.45), Orioles (6.80), Tigers (6.83), Rangers (6.85), and Cardinals (6.87). The Cardinals may have stuck around for a while in the playoff picture, but their season was not as statistically sound as the results would indicate. And I don’t think anyone will argue that the Pirates, Orioles, and Rangers have very poor pitching staffs, or that the Tigers were an all-around disappointment this season.
When we move to walks, we see that the Dodgers (3.22) once again find themselves in the top five, at the number one spot, but their “colleagues” are different. The DBacks come in second at 3.24, followed by the Twins at 3.26, White Sox at 3.31, and Indians at 3.33, meaning that the bullpens that struck out plenty of batters were not too tremendous at limiting walks. At the bottom of the heap we once again find the Orioles, Rangers, Pirates, and Tigers, with the Mariners now mixed in. See any trend emerging?
Moving to K/BB ratio, we get a mixture of the K/9 and BB/9 leaders, as the Dodgers (2.68) lead the Cubs (2.57) and Yankees (2.46), with the White Sox (2.38) and Diamondbacks (2.32) rounding out the top five. Guess who is at the bottom? Yes, the Orioles, Tigers, Pirates, Rangers, and new-found friend the Mariners. The Orioles bullpen had an ugly 1.40 K/BB. The Mariners at least registered a K/9 above 7.0, they just had issues limiting walks.
How about home runs? The Phillies, whose bullpen has been lauded for the entire season, finally break into the top five, finishing first with a 0.69 HR/9. Led by Brad Lidge and his unsustainable 3.9% HR/FB, the Phils narrowly edged the Blue Jays (0.70), the familiar Dodgers (0.73), and the Mariners and Athletics (0.78 each). When we put it all together, in the form of FIP, the ERA equivalent of controllable skills, the Dodgers led by a wide margin over all others at 3.47.
The Yankees, Phillies, and Blue Jays then ranged from 3.82-3.85. Controllable skills are not the only measure of success, but they are very important, and nobody realistically came close to the Dodgers in 2008. The Blue Jays did have a big ERA and FIP differential, as they posted the lowest bullpen WHIP at 1.25 and highest bullpen LOB rate at 79.8%. Their FIP of 3.85 suggests their 2.94 ERA was a bit lower than expected, but elite relievers are known for being able to consistently post high strand rates, low BABIPs, and other luck-based indicators that tend to normalize for starters. Based on these results, it seems the best controllable skills in the NL belong to the Dodgers bullpen, while the Yankees and Blue Jays topped the junior circuit.
Eric is an accountant and statistical analyst from Philadelphia. He also covers the Phillies at Phillies Nation and can be found here on Twitter.
Perhaps I’m mistaken, but it is my understanding that pitchers in general cannot control the amount of HR they give up other than by how many batters they can strikeout and their flyball percentage. The ratio, according to Ron Shandler’s publication, The Baseball Forecaster, that every pitcher regresses to is 10% HR/FB (though each batter has their own HR/FB ratio that they regress to, much like BABIP). Thus, a pitcher can only control their HR given up to the extent that they can strike out a lot of batters and limit the number of flyballs they give up.
So perhaps it would be better to examine their flyball to batters faced ratio (the FB%, from my understanding, is based on BIP, not batters faced), as that would control their HR rate overall.
Nice analysis overall. Diamond Mind’s Tippett’s analysis had explored how teams today need to be above average in the bullpen as well as other facets, in order to be successful and make the playoffs, so this is good stuff, as they seem to have stopped doing much analysis.
In addition, Baseball Prospectus did a study for one of their books, analyzing success in the playoffs, and found that the strikeout rate for the pitching staff as a whole was one of the few factors important for success in the playoffs. Obviously, to do that, the bullpen also has to have a high strikeout rate and a number of playoff teams did show up on top. Interestingly, all are OUT of the playoffs (it is only a small factor, but still one of the few controllable factors a team has for maximizing success), except for the Rays and the Phillies didn’t show up at all.
The Phillies probably has the edge at closer, as WRXL, was another factor, and I would think that Lidge has a much better WRXL than Perceival.
Last factor was team defense, and I have no idea which team is better.
I, like everyone else, would be interested to see how our favorite team fared. Where on this site can I find it? Thanks for the good article.