What role should Duensing have in '11?

Assuming the Twins correctly decide to keep Francisco Liriano in a Twins uniform, the biggest story line this spring will be how the team opts to fill five rotation spots with six pitchers.

Liriano and Carl Pavano have earned themselves the number one and number two spots while the size of Scott Baker and Nick Blackburn’s contracts may have provided them even chance to blow a spot in the rotation this spring. Baker has the skill set to be a very good starting pitcher while Blackburn proved late in the year that he is still capable of being a groundball-oriented workhorse the team thought they had when they extended him. Barring injury, ineffectiveness or a trade, the final spot in the rotation comes down to either Kevin Slowey or Brian Duensing. By the virtues of his 7-2 record along with a 3.05 ERA as a starter, not to mention being anointed a playoff starter, many have begun to reserve a spot in next season’s rotation for Duensing.

From his perspective, Duensing told 1500ESPN’s Joe Anderson and Phil Mackey that he wanted to enter the spring preparing for that starter role:

 “Mentally, I’m heading in there as a starter. I feel like it would be easier for me to prepare to start and then get moved to the bullpen as opposed to get prepared to be in a relief role then happen to regroup and need to work longer innings.”

For his own sake, the Twins need to make a decision on what to do with Duensing. Last season, he was pushed-and-pulled around from the relief staff to the rotation, providing the Twins with outstanding numbers in both capacities. However, he appeared spent in his final few starts having amassed a higher pitch total than his body was ready for. Is he best suited to be a starter or do his skills match that of a reliever? What role would be better for him in 2011?

Without question, Duensing brandishes a fairly strong arsenal. In fact, his slider had some of the greatest success among all of the game’s best slider-throwers. Whereas Liriano paced the league in terms of pitch value – producing a slider that was 19.0 runs above average – Duensing wasn’t that far behind. His slide piece was valued at 14.3 runs above average, 10th-best in baseball.

Because of this pitch, Duensing absolutely dominated left-handed opponents. With a minimum of 500 pitches thrown, Duensing’s .162 batting average when facing lefties was the second-lowest among southpawed starters – trailing only Texas’s CJ Wilson (.144) in that split last year. Of course, while this pitch worked well against his sinister brethren, it didn’t have the same effect on his right-handed counterparts, nor did his overall repertoire:

	OPS	Chase%	Miss%	K%	xFIP
Vs. LHB	457	32%	28%	22%	3.25
Vs. RHB	751	27%	14%	12%	4.51

(via MyInsideEdge.com & Fangraphs.com)

Despite this discrepancy, and the fact that right-handed were responsible for 10 of his 11 home runs allowed, Duensing got decent results nonetheless. Part of his success was based inciting a high number of groundballs – off both left-handed and right-handed bats – while keeping hitters from teeing up line drives.

So Duensing is what appears to be the proverbial “pitcher” rather than “thrower”. On the surface, he appears to be the kind of hurler who hits his spots, mixes up velocity and gets hitters to hit less-than-choice pitches. It’s hard to argue with his past success but does this mean that he can sustain these results going forward?

To answer that, we must acknowledge that his 2010 was very fortuitous is a lot of respects too.

Although Duensing was able to increase the amount of groundballs – jumping from 45.5% in ’09 to 52.9% last year – he had the good fortune of having a high number of those rollers and bouncers hit at his fielders. Whereas the rest of the league’s pitchers averaged a .235 BABIP on grounders, Duensing had a very low .203 BABIP – which deviated significantly from his .287mark in his 2009 tour of duty. Even if he replicates the over 50% groundball rate in 2011, I suspect we will see more hits bleed through the infield.

Likewise, while the rest of the league’s pitchers typically maintain an average of 72% of the total base runners they keep from scoring, Duensing held an amazing 81.6% of base-runners at bay – the third-highest among those with a minimum of 120 innings pitched last season. This is a statistic that tends to fluctuate at various levels but ultimately regresses back to a player’s mean. Strikeout-oriented pitchers tend to have a higher strand rate in their career based on their ability to keep hitters from putting the ball into play thereby avoiding sacrifice flies or groundballs to advance runners home. Duensing is far from a strikeout artist – better at getting lefties to whiff versus righties – so it isn’t a stretch to suggest that a few more runners will cross the plate on him in 2011.  Also, given that this hefty 2010 feat pales his previous seasons’ rates dating back to 2006 it’s safe to say that Duensing will likely not be as blessed when it comes to stranding runners in the near future.

Then there is the concern of facing more right-handed hitters in 2011 if moved to the rotation. While as a reliever, Ron Gardenhire could cherry pick innings in which Duensing would be prone to facing a higher percentage of same-sided opponents. Upon converting to a starter, opposing managers were provided the opportunity to counter by loading their lineups with righties. Nowhere did this factor play a bigger role than in Game 3 during the ALDS. The Yankees filled their lineup to the brim with right-handers, leaving only Curtis Granderson and Brett Gardner as the lone lefties in the order. Duensing was cuffed around for four runs and was removed in the fourth inning, not having enticed one swing-and-miss in 58 pitches.

Lastly, Duensing’s difference from his ERA (2.62) to his FIP (3.85) was -1.23, the fourth-highest differential among those with a minimum of 120 innings pitched. Why is this important? ERA is like a measure to a pitcher like trying to find gold with a steam shovel is: you will find some of the important stuff but you will also drag along a lot of crap with it. Like good or bad defenses behind you. FIP on the other hand, is the equivalent to using a pan and sifting for gold, you get less of the other stuff that murky the findings. While not always 100% accurate, FIP provides us with a more predictive base using data that a pitcher can control (strikeout, walk rates, home runs). Admittedly, Duensing’s FIP was solid (more so than his xFIP) but still greatly exceeds his ERA suggesting that next season, his ERA will probably be more reflective of his FIP from this season.

Given these indications, it’s not difficult to reach the conclusion that Duensing is likely to experience regression in 2011; the real question is how much will his numbers slide?

Again, because he is able to keep hitters from lacing pitches across the yard and extremely tough on lefties, he might not be a candidate to regress as hard as some would suggest based on his ERA-FIP differential would lead us to believe. After all, there are some pitchers who simply out perform their FIP in spite of high contact rates. Even so, he’s clearly a regression case when you add in the other indicators.

In order to set him up for success, the Twins should use Duensing out of the bullpen. This would limit his match-ups against right-handed foes and allow him to lean more on his slider, a pitch that he has shown success with.