We have come to accept over the past couple of years that for the most part, pitchers have the most control over their strikeout, walk and ground-ball rates. It is true that they do have some influence over a few of the metrics we lump into the luck category, but we can still be fairly accurate with our evaluations by just focusing on the three aforementioned core skills.
As fantasy players, we thrive on trying to find this season’s breakouts. Winning your league basically depends on it. The easiest way to identify these pitchers is to look at their peripherals and determine who has the ability to improve upon any of them. Better skills equal better results, assuming all else equal of course.
In my experience playing fantasy baseball and reading studies about the effect aging has on the various peripherals, it seemed pretty clear that pitchers improve their control more frequently than the other underlying skills. Luckily, we don’t have to guess anymore if this is actually the case, as Jeff Zimmerman, researcher extraordinaire, has done the work and the results can be found in this nifty graphic below.
What we find here is that the blue ground-ball percentage line tells us that starters initially see a slight uptick early and then remain rather consistent until 30 to 31. Unless the pitcher learns a two-seam fastball to generate more sink or changes his pitch mix or location to induce more ground balls, it is pretty difficult for him to radically shift his ground-ball rate. As expected, a pitcher’s strikeout rate (the red line) is almost in decline from the beginning, which not surprisingly makes it the hardest skill to improve upon.
Last, we find the yellow line representing walk rate and, lo and behold, it declines nicely from 21 through 26 to 27. This backs up the anecdotal evidence and how we generally view younger pitchers with the expectation of improved control in their future.
To search for these potential breakouts driven by improved control, I looked at all starters with at least 100 innings pitched in 2011, and filtered them using a minimum 6.8 K/9 (just a hair above the 6.75 league average rate for this group) and 45% ground ball rate (right above the 44.4% group average). I then considered those pitchers with ERAs north of 4.00 who have struggled with their control and are still relatively young.
Here are the four best candidates in which a control improvement could drive a breakout season:
|Chad Billingsley ||7.3||4.0||45.3%||4.21|
|Felipe Paulino ||8.7||3.6||45.1%||4.26|
|Jake Arrieta ||7.0||4.5||45.7%||5.05|
|Edinson Volquez ||8.6||5.4||52.4%||5.71|
Chad Billingsley 
For a 28-year-old pitcher with a career 3.68 ERA and two seasons with sub-3.50 marks, it is hard to label Billingsley a true breakout candidate. However, 2011 was quite a disappointment, as he posted the highest ERA of his career. His skills dove after the all-star break, as his strikeout rate collapsed and walk rate jumped, resulting in a 4.77 ERA. There have been no whispers of anything injury related, so it is important not to overweight just 71.2 innings of performance.
Billingsley has only once posted a league-average walk rate, and that was right at the league average in 2010. Interestingly, his first-strike percentage has been nearly identical every season since 2008, though his 2010 was actually his lowest mark. They have centered right around the league average, which does suggest he deserves a better walk rate.
We cannot automatically assume that his strikeout rate will rebound, but his fastball velocity was the same as 2010 and remained stable all year. He has always been a ground-ball pitcher, so even if his strikeout rate does not fully recover, a drop in walk rate should be enough to push his ERA back below 4.00.
Felipe Paulino 
Paulino had been a favorite of mine after posting a 3.93 SIERA and 11.6% swinging strike rate in 2009, but I lost interest when he was traded to the Rockies after the 2010 season. Now back in the starting rotation and in a home ball park that suppresses home runs and is more neutral to overall run scoring, I am intrigued once again.
In actuality, the 28-year-old Paulino does not truly have to improve his control all that much to experience a breakout. He did struggle with the walks in 2010 and has had a checkered history before that, but he posted a 3.4 BB/9 in 2009 and a 3.6 mark last season. Surprisingly, his F-Strike% was over 61% in 2010 when his walk rate was inflated, but that provides optimism that he does have the ability to throw more first-pitch strikes in the future.
With his 95 MPH fastball and excellent slider, he should continue to pile up the punchouts, though his ground-ball rate is bordering on the league average. Besides dreaming of what a further improvement in control can do for Paulino, another key to his results is defensive support. He sports a grotesque .340 career batting average on balls in play, but in just 347.2 innings, it is too early to tell whether he is legitimately lacking in the prevention of hits on balls in play.
Jake Arrieta 
You may not remember this, but Arrieta was pretty recently one of the Orioles top prospects. You wouldn’t remember because his performance has caused most to cross him off their draft lists and completely forget about him. With a career 4.88 ERA and 4.90 SIERA in just about a season’s worth of innings, no one would fault you for such action. To make matters worse, his 2011 season ended early after undergoing surgery to remove a bone spur from his throwing elbow in August.
His name found its way to this list, though, and that provides an opportunity to scoop up a potential breakout performer for peanuts. The soon-to-be 26-year-old Arrieta has never displayed great control and his Minor League performance has been a mixed bag. At two stops he posted a sub-4.0 BB/9, while at two others, his walk rate topped the 4.0 mark. With the Orioles, his control has been weak, as his career mark sits at 4.38.
His F-Strike% does not give us much hope that improved control is forthcoming. Of course, that’s half the point of this article — control improvements aren’t typically telegraphed, they just happen as young pitchers mature. However the potentially good news brings us back to his elbow surgery. Elbow issues are usually said to affect a pitcher’s control, which may very well have been the case last year. If his elbow is now fixed and he is fully healthy this season, it follows that his walk rate could improve.
Edinson Volquez 
I have been a Volquez fan boy ever since I picked him up post-draft, but before the season began, for his breakout 2008 campaign. There is something intoxicating about watching him throw a mid-90s fastball and then watching the hitter flail at the next pitch, his trademark changeup. Volquez is basically the mascot for this list as he fits the profile perfectly. Does he strike out hitters at a strong rate? Check. Does he induce ground balls? You bet. But, he usually cannot find the plate.
Volquez’s best walk rate since that exciting 2008 season came that year, but it was still rather poor at 4.3 per nine. Amazingly, the 28-year-old has not posted a walk rate below five since. Some of it can probably be blamed on his recovery from Tommy John  surgery, but he underwent the procedure back in August of 2009. That means he entered the 2011 season 19 months after having the operation, which should have been more than enough time to get his control back in order. We usually see pitchers struggle with their control initially when returning, but at some point the control does return to normal levels.
Unfortunately, there is absolutely nothing in his history or really any deep esoteric metric that suggests any type of leap in control is imminent. So once again, drafting Volquez requires blind faith and optimism, but is the very reason why he appears on this list. And yes, the move to PETCO Park will certainly help (and put him on some sleeper lists for sure), especially after he posted a ridiculous 20.7% home run per fly ball ratio last year, but it won’t magically improve his control.