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What Happened To Brian Duensing?

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Brian Duensing hasn't contributed very much to the Twins this year. What's been the source of his struggles?

Dennis Wierzbicki-USA TODAY Sports

During the offseason, the Twins made a somewhat controversial decision to offer arbitration to Brian Duensing. To the organization, it probably wasn't that big of a deal, but to many fans it was an odd choice considering his price tag (roughly $3.5 million) and limited role in the bullpen. If he were a setup man, that would have been fine, but Duensing was more of a situational lefty, a LOOGY (Lefthanded One Out GuY) if you will.

Additionally, if Duensing had been coming off his 2013 season, the cost of retaining him would have been a little more justifiable. Yeah, the 3.98 ERA wasn't pretty, but it was backed up by an 8.26 K/9, 0.59 HR/9, and 3.24 FIP. His ERA was only so high because of a .348 BABIP, though admittedly he was a better pitcher against righties (.258/.348/.364) than lefties (.298/.344/.443).

However, the offer of arbitration came after the 2014 year. His ERA of 3.31 looked better, but the secondary stats had faltered. His strikeouts dipped to 5.47 per 9 innings, he was now allowing nearly one home run per 9 innings, and his FIP was a mediocre 4.51. But, he remembered how to neutralize lefthanded hitters, allowing a triple-slash of .235/.282/.305, while forgetting how to retire righties by letting them hit /.264/.352/.491.

As a reliever that averages less than one inning per appearance, it's easier for one's numbers to fluctuate. Thus, why don't we also take a look at Duensing's career numbers as a reliever.

AVG OBP SLG K/9 BB/9 HR/9 ERA FIP
.253 .328 .368 6.11 3.32 0.59 3.71 3.80

idk my bff Jill AVG OBP SLG
vs. lefties .233 .283 .326
vs. righties .292 .356 .464

What I see here is that Duensing has been a pretty decent reliever for his career. The ERA and FIP aren't special, but Duensing limits home runs very well and he's pretty good at shutting down lefthanded batters. Meanwhile, he doesn't strike out many hitters nor does he know how to retire a righty.

This season, Duensing's struggles have been well-chronicled. There's maybe two positive stats to note - his HR/9 and groundball rates are career bests at 0.45 and 54.7%, respectively - and just about everything else has been negative.

AVG OBP SLG K/9 BB/9 HR/9 ERA FIP
.280 .384 .405 4.50 4.50 0.45 6.30 4.53

omg wtf bbq AVG OBP SLG
vs. lefties .324 .425 .412
vs. righties .244 .348 .400

The most glaring numbers to me are Duensing's strikeout and walk rates, coupled with his triple-slash against lefties. He's once again failing to retire them, and at the same time he's not striking out many hitters. Now, although his career K/9 rate in relief is 6.11, that was boosted a bit by 2013's rate of 8.26. Every other non-2015 season, Duensing has been right around 5 to 5.50 K/9, so the 4.5 K/9 this season isn't a huge drop. Remember how I said earlier that a pitcher averaging less than one inning per appearance will have fluctuations? Well, all Duensing would need to do to get that K/9 back in line would be to strike out three batters over his next two innings. That's certainly not an impossible task.

Another stat that jumps out is Duensing's strand rate. Major league pitchers typically strand just under 3/4 of their baserunners, but this year Duensing has only prevented 60% of his opponents from scoring once reaching base. Now I did some digging on FanGraphs, and it turns out that the strand rate does not include baserunners that are inherited by other relievers. Therefore, that 60% are only the runners that Duensing himself keeps on base, and it's not as if Michael Tonkin comes in and is responsible for them.

Finally, there's one last thing that I found interesting. I'm a big fan of pitch F/X and I figured I'd do a little digging. I've put together a GIF below of the pitch movement for Duensing since 2013, and I want to see if you can spot the subtle difference.

Duensing 2013-2015 Pitches

Now, I have no idea if this is actually significant, but all of Duensing's pitchers have gradually moved closer towards a righthanded batter (source: Texas Leaguers).

I got nothing Horizontal 2013 (in) Horizontal 2014 (in) Horizontal 2015 (in) 2013-2015 Difference
4-seam FB 6.72 6.28 5.70 -1.02
Sinker 10.90 10.17 9.38 -1.52
Slider 0.31 -1.26 -1.88 -2.19
Change-up 10.71 10.65 9.51 -1.20
Curve -3.05 -2.90 -3.40 -0.35

The curveball is negligible, but everything else has moved either an inch or two away from a lefty. Again, I'm not sure if it's the culprit for Duensing's struggles, but baseball is called "a game of inches," where just a slight change in placement can mean the difference between a home run and a long fly out. While a little extra sweep on his slider is probably a good thing, I feel that throwing a slightly straighter fastball cannot be beneficial.

I strongly feel that Caleb Thielbar would be a better option on the roster than Duensing, but Thielbar isn't pitching well in Triple-A and so a call-up won't come in the near future. The Twins could be interested in acquiring a lefty reliever as the trade deadline nears, but they also axed Aaron Thompson for Ryan O'Rourke while giving Duensing back late-inning opportunities in the process. They may be content that his stretch of eight consecutive scoreless innings are a sign of his resurgence. With the bullpen currently a mess, any positive contributions from Duensing over the rest of the season will certainly be welcomed.