As the Twins crawl to a second consecutive disappointing season, basically every silver lining that surrounds this team has been exhausted by fans throughout our efforts to remain interested. Josh Willingham is just the third Twinkie to ever crank 35 homers. Ryan Doumit has been a nice bargain. Joe Mauer is healthy again and gets on base more than any player in baseball. And oh yeah, the bullpen went from a 4.51 ERA In 2011 to a 3.66 ERA in 2012.
How comfortable should the Twins be going forward with this group of relievers, though? It’s pretty obvious that Glen Perkins has transformed himself into a dominant late-inning option. Jared Burton is lethal to right-handers and should be a useful setup piece in 2013. Ditto Brian Duensing from the left-hand side. Tyler Robertson’s overall numbers aren’t great, but he’s fanned 31 percent of the lefties he’s faced as well.
My biggest concern for the 2013 bullpen is that the Twins make the mistake of looking at Alex Burnett and thinking of him as a viable candidate for meaningful innings (assuming, of course, there are meaningful innings to be played – here’s hoping). His superficial numbers – specifically his 3.29 ERA – are appealing upon first glance, but he carries a lot of red flags
There are 197 pitchers in baseball this season who have thrown 30 innings or more. Of those 197, the two lowest strikeout percentages belong to a pair of Minnesota Twins. Jeff Gray, mercifully, has been removed from the picture. He, however, still managed to top Burnett’s mark of 10.2 percent.
I think everyone’s pretty aware that Burnett hasn’t exactly missed many bats this season, but to fan fewer than any reliever in the game and still sport a 3.29 ERA requires some good fortune. Let’s take a look at his pitches.
PitchFX breaks Burnett’s repertoire down into four pitches: a four-seam fastball, a two-seam fastball/sinker, a slider and a curveball. He actually generates reasonable swinging strike rates on the four-seamer, slider and curve. Only his two-seam fastball struggles, with just a 3.8 percent swinging strike rate, but this is the pitch he throws the most:
Four-Seam – 23.6 percent, 257 total thrown
Two-Seam – 38.3 percent, 417 total thrown
Slider – 18.7 percent, 204 total thrown
Curveball – 17.4 percent, 189 total thrown
The lack of swings and misses are mitigated (to an extent), however, by his near-53 percent groundball rate on the two-seamer. His four-seam fastball, on the other hand, has been hammered throughout his career despite a higher swinging strike rate:
Four-Seam – .316/.396/.456 opponent batting line
Two-Seam/Sinker – .240/.333/.341 opponent batting line
Slider – .233/.270/.342 opponent batting line
Curveball – .250/.280/.444 opponent batting line
All of this contributes to Burnett having the fourth-worst Skill-Interactive ERA (SIERA) of any relief pitcher in Major League Baseball this season among those with 30 or more innings (he’s actually worst among qualified relievers). Burnett’s 4.69 mark is only better than those of Rafael Dolis, Miguel Batista and Jeff Gray, respectively. For those unfamiliar with SIERA, here’s an "in-a-nutshell" description, courtesy of Matt Swartz at FanGraphs:
…[SIERA] follows in the footsteps of xFIP by using statistics that don’t change much from year-to-year: strikeout rate, walk rate and ground-ball rate.
When Eric Seidman and I developed the original SIERA — which appeared at Baseball Prospectus more than a year ago — we didn’t totally appreciate why it worked. Essentially, since it uses regression analysis, it asks the question: What’s the typical ERA for pitchers with similar strikeout, walk and ground-ball rates in recent years?
Our thought was that the main reason SIERA worked so well was that it took into account the interplay between those three statistics. But on further analysis, it turns out that SIERA is successful mainly because it assumes a low BABIP and HR/FB for strikeout pitchers (and for fly ball pitchers, as well).
In other words, SIERA is basically stating that Burnett has been tremendously lucky this year. He has a .275 BABIP, which is something one would expect from a high-flyball, high-strikeout pitcher. But Burnett strikes out just one of every 10 batters he faces and is a groundball artist who induces more than 51 percent worm-burners. Comparing that skill set to others in recent history, Burnett’s ERA should be leaps and bounds higher. The 4.69 number may not seem terrible, but it’s the 11th-worst single-season SIERA mark of any qualified reliever from 2010-12.
Obviously this is pretty harsh on Burnett. I actually think there’s a decent chance that he could develop into a reliable Major League reliever. The problem is that the Twins have never given him a chance to do that at Triple-A. Burnett strikes me as someone who could benefit from additional time at that level, but it seems a long shot to happen now.
The Twins have long stated that they like Burnett’s arm, and as a result they’ve kept him at the MLB level despite being over his head. Odds are that he’s being looked at as a piece for 2013 because he’s posted a respectable ERA this season despite his putrid peripheral numbers. There’s also the matter of his service time. Depending on what date is deemed the cutoff for Super Two eligibility, Burnett could end up as a Super Two reliever who would then be eligible for arbitration this offseason. Ben Nicholson-Smith at MLBTR noted a few weeks back that Burnett is one of a few players that is right on the borderline.
If Burnett is going to play at this level in 2013, it seems like he’s in need of a serious change in repertoire. I’m far from a Major League pitching coach, so tweaks to Burnett’s arsenal will have to come down to him and Rick Anderson. I’m willing to bet, though, that without a major change to his mix of pitches, Burnett’s seemingly impressive ERA isn’t long for this world. I know the Twins aren’t renowned as a stat-heavy team, but hopefully the fact that Burnett fans a fewer percentage of opponents than any fireman in the game is something they recognize the need to address.