It is my job to write an introduction right now. This means thinking about some appealing way to present the topic, using language in a way that effectively communicates to you what is ahead, perhaps something funny or novel, a metaphor, an anecdote. Words that are useful, basically. And to do it efficiently, so I don't lose you before the GIFs start. That's what an introduction is, and that's what my job is right now.

But what if my job was to write an introduction that does none of those things? If, in fact, the more of those things that I did, the worse the introduction was? Then my job would be so much easier! It would have taken me about 1/12th as long as my actual introduction-writing task took, because I would just copy some excerpt from whatever page I had open in a different tab, paste it here, like 

. In
ILLNESS,” the narrative voice
says, “I’m separate from the
author. Like a moth, I have fur
on my ba

And I would be done! Yesssssss.

So that's what intentional balls are like, basically. They are the thing a pitcher does that is the least like the thing that a pitcher is paid to do. It takes willfully incompetent competence to screw that job up. People screw that job up! This is the year in intentional balls, some of them screwed up, some just unusual. 

Hardest-thrown intentional ball. 
Here's the hardest-thrown intentional ball of the year, which was 92.1 mph, and thrown by Kelvin Herrera

Kelvin Herrera threw the hardest average fastball in baseball this year, at 98.5 mph. There are a billion statistics—I don't know if this is a statistic as much as it's a measure, but the first sentence of Wikipedia's entry for "statistic" (as opposed to "statistics") is "a single measure of some attribute of a sample" so I guess they're the same thing—and some of them are great to lead the league in, such as OPSBI, and some are not as great to lead the league in, such as wild pitches, and then there are the ones that are value-neutral but descriptive, like percentage of split-fingered fastballs thrown. Average fastball velocity has a bit of all three. Knowing that Herrera threw the hardest average fastball this year, we know he: 

1. Throws a fastball, and on average it's very fast, so he's that kind of pitcher (value-neutral, descriptive)
2. Throws a fastball very fast, which is a very significant key to a fastball, as noted by its name (good indicator)
3. Probably is a reliever, which means he probably is not the best pitcher in the league, on his team, or in any single game in which he appears (bad indicator)

In fact, as a single statistic on its own, it's terribly unhelpful for predicting future success. Here are the past eight pitchers to lead baseball in average fastball velocity, and their value the following season: 

Year Pitcher Next year WARP
2011 Henry Rodriguez -0.5
2010 Joel Zumaya 0
2009 Jonathan Broxton 0.8
2008 Brandon League 0.3
2007 Matt Lindstrom 1.2
2006 Joel Zumaya 0.4
2005 Bobby Jenks 1.7
2004 Billy Wagner 2.1
Which is all just to point out that Kelvin Herrera throws really, really hard. And so a 92.1 mph intentional ball is acceptable coming from him. Henderson Alvarez, on the other hand, is trying too hard:
Alvarez throws his average fastball 93.3 mph, so this intentional ball—at 91.4 mph—is nuts. The average intentional ball thrown this year was about 77 percent of the pitcher's typical fastball speed. Alvarez throws this intentional ball 98 percent as hard as his typical fastball. Earlier in the at-bat, in fact, after a 90.5 mph intentional ball, Jeff Mathis admonished Alvarez to check his self before he wrecked his self: 

To which Alvarez replied that he has gum. 
Communication, folks. 
Slowest Intentional Ball. 
Here we have an inconclusive answer to the question. The answer, as we have it, is Brayan Villarreal, who threw this pitch 41 mph lololol.
The thing is, his next three pitches looked just as slow, but none of them show up in PITCHf/x. Not at all: not in queries, not on online PITCHf/x tools, not on MLB's Gameday description of events. In some instances, the entire at-bat has been eradicated from history. Colin Wyers reports that "there is a minimum speed at which the system is going to fail to record a trajectory at all," which is evidence that the next three pitches might have been slower than this one. Here's a screengrab of one of the three, which shows that either Brayan Villarreal is really, really bad at this, or that Alex Avila was daydreaming that he just caught the final strike of the World Series:  
Wildest Intentional Ball (Horizontal).
Jake Diekman throws an intentional ball perfectly here, suuuuuper intentional and definitely a ball.

What's beautiful about it is that the batter is A.J. Ellis
Catcher: We're going to intentionally walk this guy.
Pitcher: Cool. This is my first day on the job, so I apologize if this is a dumb question, but
Pitcher: What does that mean? 
Catcher: Just throw a pitch that the batter would never, ever in a million years swing at.
Pitcher: So, for this guy, A.J. Ellis, that would be…?
Catcher: Pretty much right down the middle would be fine. 
Diekman took no chances. Diekman's got a funny pitching motion, and pitching in general is funny, but watching him pitch frame-by-frame is galling. This is what Jake Diekman looks like in reverse. 
Wildest Intentional Ball (Vertical). 
Furbush can't competently throw an intentional ball, but at least he knows the rule that if a fan asks for a ball you must throw it to him on the next live pitch.
Best (Worst) Intentional Ball. 
There are three champions for this one, because there are three ways you could answer this. The least-outside pitch was thrown by Tim Lincecum, which was 3.8 inches from the center of the plate. Not 3.8 inches from the strike zone; 3.8 inches from the very middle of the strike zone, at least horizontally. 
Delightfully, Aaron Hill seems to be so surprised at the trajectory of the pitch that he actually ducks out of the way a little bit. Maybe. He's either doing that or he's ducking down to make sure the pitch isn't called a strike on him. Either way!
The closest pitch to the center of the strike zone is this one, by Jose Mijares to Hanley Ramirez
But it doesn't really look like it's close to a strike—Jose Molina would probably get a called strike on it, but whatever—and even if Hanley Ramirez decided to swing at it it's not in a hittable location. Mijares basically throws a good pitch that he's not trying to: 
But the truly worst intentional ball thrown this season was by the Brewers' Tim Dillard, to Brandon Belt
It's clearly hittable, but it is not, alas, so hittable that Brandon Belt had no choice to hit it. And so we missed out on a potentially much-more-GIFfable event. 
So I guess the question is, if pitchers are so bad at this—even only occasionally—is there a way around it? Could a pitcher, for instance, simply wind up and toss the ball a few inches, go pick it up himself, do it again, and walk the hitter without ever risking this or this? I don't see anything in the rules about it, though to be honest I'm not going to spend more than 45 minutes looking. But at a certain point, I suppose, some tasks shouldn't be too hard for professional athletes to just go ahead and do. Throwing an intentional ball would qualify.