Here's what we know about pitching in 2018, headed into 2019: It's really, really good.
"I think the pitchers are just super nasty now," free-agent pitcher Adam Ottavinotold us recently, "and that's my diagnosis of why guys are striking out a lot." 
He's not wrong. But how do we measure who had the year's best pitches? It's not exactly a simple question, because pitches don't exist in a vacuum. That 95 mph fastball you just saw for a third strike may have been perfectly set up by the perfectly tunneled change up or slider before it. If pitching is about disrupting timing, then it's important to know what the hitter is expecting, and that means all of a pitcher's offerings have to work in concert.
That, of course, gets pretty complicated, so we're going to keep it simple here, as we did last year. Let's look at the outcomes of each pitch type, using a metric we call "Expected Weighted On-Base," which allows us to look at both the amount of contact and the quality of contact, independent of ballpark and defense.
The 2018 Major League average was .311. But as you can see, that's not evenly distributed across pitch type. Fastballs get hit harder than that, and breaking pitches have better outcomes. This is exactly why there's fewer and fewer sinkers in today's game, and more and more sliders. 

So, setting a minimum of 300 pitches for four-seamers and sinkers, and 250 for other pitch types, which pitchers had the most dominant pitches this year? We'll split it into starters and relievers. 
Four-seam fastball
Starters
.250 -- Walker Buehler, Dodgers
.251 -- Max Scherzer, Nationals
.261 -- Jacob deGrom, Mets
.262 -- Chris Sale, Red Sox
.268 -- Carlos Martinez, Cardinals
We're off to a good start, because Scherzer, deGrom, and Sale are pretty clearly three of the five or so most dominant pitchers in the game, and Sale and deGrom each made this list last year, too. Plus, there's a strong argument to be made that Buehler is better than teammate Clayton Kershawright now, and part of that is definitely because of his four-seamer, which averages 96.2 MPH, touches 100, and carries a 30.8 percent whiff rate that was among the best in the game. 
Relievers

.198 -- Sean Doolittle, Nationals
.254 -- Juan Nicasio, Mariners
.255 -- Josh Hader, Brewers
.257 -- Edwin Diaz, Mariners
.257 -- Nick Wittgren, Marlins
.257 -- John Brebbia, Cardinals
Doolittle makes a tremendous amount of sense here, because he throws his four-seamer nearly 90 percent of the time, more often than anyone, and if you're throwing a pitch that often, it had better be good. Same goes for Diaz and Hader, two of (if not the two) most dominant relievers in baseball. 
But it's some of these other names who really stand out, in a surprising way. New Phillie Nicasio was far, far better than his 6.00 ERA would indicate, while Miami's Wittgren quietly had a 2.94 ERA, using his deceptive delivery to collect 27 of his 31 strikeouts with an otherwise unimposing fastball. 
Two-seam fastball / sinkers
Starters
.235 -- Zack Wheeler, Mets
.235 -- Anthony DeSclafani, Reds
.257 -- Buehler, Dodgers
.264 -- Brad Keller, Royals
.265 -- Aaron Nola, Phillies
After years of injury problems, Wheeler finally stayed healthy in 2018 and had a breakout season. The sinker isn't his best pitch, but he certainly leaned on it more as the season progressed, using it only three percent of the time in April, up to 26 percent by August. There's Buehler again, and Nola, and perhaps the only highlight of DeSclafani's season.
Relievers

.194 -- Ottavino, Rockies
.224 -- Adam Cimber, Padres / Indians
.235 -- Tim Hill, Royals
.257 -- Jared Hughes, Reds
.258 -- Craig Stammen, Padres
Ottavino is best known for his frisbee slider, but he made some serious fastball changes in 2018, de-emphasizing his four-seamer while upping usage of his sinker, from 18 percent to 42 percent. He threw it 529 times and allowed only three extra-base hits, so it's safe to say that was a wise choice.
"Although I am a heavy two-seam pitcher," Ottavino said, "I try to be a strikeout pitcher, so I don't try to use it for contact."
Cimber might be best remembered as "the other guy" in the trade that sent Brad Hand to Cleveland for Francisco Mejia. While he struggled in Ohio, he had been fantastic as a Padre, piling up a 51/10 strikeout/walk ratio. 
(Where's Blake Treinen, you ask? He rated very well, but there's also some evidence that Oakland's strong infield defense -- thanks, Matt Chapman! -- made his sinker look a little better than it was. It was still outstanding, of course.)
Cutter / slider
Starters
.158 -- Dylan Bundy, Orioles 
.160 -- Sale, Red Sox
.172 -- James Paxton, Mariners
.178 -- Trevor Bauer, Indians
.186 -- Carlos Rodon, White Sox
In what was otherwise a trying season for Bundy, who had a 5.45 ERA for the Orioles, there was still this bright spot. All of his other pitches combined to be hit for a .317 average and a .590 slugging, but his slider was far better, allowing just a .178 average and a .370 slugging. The next three pitchers here are rightfully considered among the best in baseball, and Rodon's slider has long been his calling card. Next on this list would be Patrick Corbin, who just rode his deadly slider to a big contact with Washington.
Relievers

.101 -- Albertin Chapman, Yankees
.126 -- Hader, Brewers
.139 -- Will Smith, Giants
.153 -- Jose Leclerc, Rangers
.157 -- Edubray Ramos, Phillies
This is a great example of how no pitch exists in a vacuum, because it's pretty clear that the requirement that batters respect Chapman's triple-digit fastball makes his slider play up. Perhaps because of that, Chapman threw his slider a career-high 25 percent of the time, and the results were phenomenal, as he allowed only two extra base hits and piled up the highest swing-and-miss rate of any slider in the game.
You're not surprised to see Hader here, obviously, and Smith (2.55 ERA) and Leclerc (1.56) had years that didn't get nearly as much notice as they ought to have. Diaz and Treinen are next on this list, for what it's worth. Great pitchers tend to have more than one good pitch.
Curveballs
Starters

.133 -- Justin Verlander, Astros
.134 -- Blake Snell, Rays
.140 -- Lance Lynn, Twins / Yankees
.171 -- Mike Clevinger, Indians
.177 -- Jack Flaherty, Cardinals
Among those who just missed the top five here: Nola, Charlie Morton, and German Marquez. Verlander's curveball is probably his third-best pitch, but it's also really, really good. In 2018, that pitch collected 66 strikeouts and allowed just three extra-base hits. 
We were a little surprised to see Lynn make this list, and he only just barely made the cut, but the numbers were impressive, allowing only a .149 average and three extra-base hits.
Relievers
.133 -- Keone Kela, Rangers / Pirates
.140 -- C.J. Edwards, Cubs
.151 -- Jace Fry, White Sox
.153 -- Taylor Rogers, Twins
.160 -- Wade Davis, Rockies
Davis aside, it feels like maybe you don't know these names, and you should. Did you realize that Fry had a Top-20 strikeout rate last year, higher than Treinen or Player Page for David Robertson? Had you noticed that Rogers had a 0.94 ERA in the second half and held hitters to a .118/.204/.152 line? They may not be household names, but you'll want to know them in 2019.
Changeups 
Starters

.164 -- Kenta Maeda, Dodgers
.188 -- Joe Musgrove, Pirates
.195 -- deGrom, Mets
.196 -- Stephen Strasburg, Nationals
.200 -- Scherzer, Nationals
Another list, another grouping of some elite pitchers in deGrom, Strasburg, and Scherzer. Maeda started talking in spring about using his changeup, and a new grip apparently helped make it even more effective as the season went on. Maeda (along with Rodney and Strasburg) finished in the top five of the changeup whiff rate leaderboard, further evidence of how impressive the pitch was.
Relievers
.147 -- Juan Minaya, White Sox
.151 -- Tony Watson, Giants
.193 -- Kevin McCarthy, Royals
.201 -- Fernando Rodney, Twins / A's
.204 -- Erik Goeddel, Mariners / Dodgers
Rodney has made a career out of that changeup, but we'll admit that otherwise this is the most random assortment of names we'll have to offer. Minaya, for example, hasn't quite broken out because he has trouble throwing strikes, but his changeup was an outstanding pitch in 2018. (And it's new, too; he threw it only three percent of the time in 2017, and nearly 25 percent of the time in 2018.) While Watson has long been a reliable reliever, now you know something a little about McCarthy and Goeddel, too.