So many pitchers are defined by a specific pitch type -- take Mariano Rivera and his cutter, or Nolan Ryan and his fastball. Certain pitches give a batter practically no chance.

Which offerings fit this description in 2019? To answer this question, we took a look at each pitch type, separating out starters and relievers. Like when we looked at hitters, the evaluative metric was expected weighted on-base average (xwOBA), which adds quality of contact (exit velocity and launch angle) to strikeouts and walks.

Here are the top-five lists for each pitch type, with pitches-thrown minimums to give us sample sizes of at least 55 pitchers (pitchers are listed with their current organization):

Four-seam fastballs

Starters, min. 400 thrown
137 pitchers

1. .245 -- Gerrit Cole, Yankees
2. .264 -- Brandon Woodruff, Brewers
3. .268 -- Blake Snell, Rays
4. .273 -- Adrian Houser, Brewers
5. .275 -- Chris Paddack, Padres

Cole had 178 strikeouts on four-seamers in 2019, 34 more than any other pitcher. Since the start of 2018, he has 67 more than anyone else -- with 302 strikeouts on the pitch.

Relievers, min. 300 thrown
129 pitchers

1. .194 -- Emilio Pagán, Rays
2. .199 -- Brandon Workman, Red Sox
3. .228 -- Seth Lugo, Mets
4. .234 -- Pedro Báez, Dodgers
5. .236 -- Tyler Duffey, Twins

Pagan had a 36.0 percent whiff rate on his four-seamer, fourth among relievers with at least 50 swings against four-seamers. Josh Hader led the way in that category at 40.9 percent -- but his xwOBA on the pitch was .254, good for ninth on the list.

MLB average: .354 xwOBA

Two-seamers and sinkers

Starters, min. 250 thrown
89 pitchers

1. .247 -- Eduardo Rodriguez, Red Sox
2. .268 -- Aaron Civale, Indians
3. .269 -- Brandon Woodruff, Brewers
4. .272 -- Julio Teheran, Angels
5. .273 -- Jack Flaherty, Cardinals

In the second half, Flaherty allowed just five hits on his two-seamer, with opponents going 5-for-42 (.119) in at-bats ending on the pitch.

Relievers, min. 250 thrown
66 pitchers

1. .224 -- Seth Lugo, Mets
2. .261 -- Aaron Bummer, White Sox
3. .270 -- Jordan Hicks, Cardinals
4. .272 -- Adam Ottavino, Yankees
5. .273 -- Wade LeBlanc, free agent

Ottavino’s xwOBA on his sinker was up from the .202 mark he posted in 2018, but there’s no denying how dominant the pitch has been over the last two years. In that span, his .233 xwOBA on his sinker is lowest in the Majors among pitchers to throw at least 400 two-seamers and sinkers.

MLB average: .358

Cutters and sliders

Starters, min. 300 thrown
99 pitchers

1. .175 -- Justin Verlander, Astros
2. .194 -- Noah Syndergaard, Mets
3. .198 -- Frankie Montas, A’s
4. .199 -- Elieser Hernandez, Marlins
5. .202 -- Patrick Corbin, Nationals

Corbin led the Majors with 161 strikeouts on cutters and sliders, 34 more than second-place Verlander. Corbin’s teammate, Max Scherzer, just missed the list, at sixth with a .207 xwOBA.

Relievers, min. 250 thrown
112 pitchers

1. .133 -- Ken Giles, Blue Jays
2. .139 -- Liam Hendriks, A’s
3. .149 -- Tanner Rainey, Nationals
4. .165 -- Buck Farmer, Tigers
5. .174 -- Roberto Osuna, Astros

Giles used his slider 49.4 percent of the time in 2019. Hiis overall xwOBA of .245 was also in the 98th percentile across the league.

MLB average: .282

Curveballs

Starters, min. 250 thrown
80 pitchers

1. .111 -- Tyler Glasnow, Rays
2. .171 -- Chris Bassitt, A’s
3. .183 -- German Márquez, Rockies
4. .186 -- Lance Lynn, Rangers
5. .187 -- Anthony DeSclafani, Reds

Charlie Morton just missed here, in sixth at .192. He gets a mention since he led the Majors in curveball strikeouts, with 136. Márquez was third on that list, with 108, just behind Aaron Nola (109).

Relievers, min. 150 thrown
57 pitchers

1. .092 -- Yusmeiro Petit, A’s
2. .156 -- Jerry Blevins, free agent
3. .168 -- Derek Law, Blue Jays
4. .173 -- Nick Anderson, Rays
5. .174 -- Scott Barlow, Royals

Petit threw just 162 curveballs, but they were practically unhittable -- he allowed just four hits on those, and only one of those was for extra bases. Though his 2019 curveball results were extreme, he had a .216 xwOBA on his curve in 2018, so this isn’t anything too new.

MLB average: .269

Changeups and splitters

Starters, min. 300 thrown
65 pitchers

1. .141 -- Yonny Chirinos, Rays
2. .193 -- Stephen Strasburg, Nationals
3. .194 -- Luis Castillo, Reds
4. .199 -- Homer Bailey, Twins
5. .208 -- Jacob deGrom, Mets

Castillo and his changeup were a force to be reckoned with in 2019. He had 155 strikeouts on the pitch -- nobody else had more than 76 on changeups or splitters.

Relievers, min. 150 thrown
61 pitchers

1. .171 -- Roberto Osuna, Astros
2. .177 -- Michael Lorenzen, Reds
3. .178 -- Touki Toussaint, Braves
   4-T) .191 -- Tommy Kahnle, Yankees
   4-T) .191 -- Brandon Kintzler, free agent

Kahnle notched 68 strikeouts on his changeup in 2019, good for the sixth most in baseball and most among relievers.

MLB average: .286

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Those leaderboards feature plenty of fun names, but here are five big takeaways.

1) A full season of Tyler Glasnow is going to be a ton of fun to watch

Glasnow got off to a terrific start in 2019 before his season was shortened due to injury, living up to the top-prospect hype that had surrounded him for years. His .111 xwOBA on his curveball is the lowest of any starter on the lists above, and though his four-seamer didn’t make the lists, it was also a great pitch for him, with an average velocity of 96.9 mph.

Glasnow’s curveball basically meant curtains in 2019. He had a 33.6 percent putaway rate on the pitch, the highest of any pitcher to throw more than 100 two-strike curveballs. That means that more than a third of the time, if he threw a two-strike curveball, the batter struck out.

2) Seth Lugo is more than just elite curveball spin

When Lugo first got to the Majors, he wowed the Statcast-aware fan with his curveball spin rate. He lived up to that reputation yet again in 2019, when his average of 3,285 rpm was second behind Ryan Pressly among pitchers to throw at least 100 curves.

But he also showed he could be elite with the fastball, too, making our top-five lists for both four-seamer and sinker xwOBA. His .195 curveball xwOBA in 2019? That just missed the top-five list for relievers. Lugo’s continued development and success is a key component in any prediction of a bounce-back season for the Mets’ bullpen in 2020.

3) The Rays have nasty stuff

Glasnow was discussed above, but he’s hardly the only Rays pitcher appearing on these lists. We also have Blake Snell and Emilio Pagán for four-seamers, Nick Anderson for curveballs and Yonny Chirinos for changeups and splitters. In other words: beware of Rays pitching.

We know the Rays were second in the Majors last year with a 3.65 ERA, but this allows us to go beyond that. They were third in team xwOBA against, at .289, behind the Astros and Dodgers. What about a singular pitch type? Take your pick: they were second among teams in xwOBA against four-seamers (.306), second against curveballs (.215) and fourth against changeups and splitters (.260).

4) Good luck hitting a Brandon Woodruff fastball

After being primarily a reliever in ‘18, Woodruff became a full-time starter in ‘19, and his stuff still played well. He’s on second on the starters’ four-seamer xwOBA list at .264 behind only Gerrit Cole, and third on the equivalent list for sinkers.

Those two pitch types made up 64 percent of the pitches he threw in 2019, so he knows how to play to his strengths. He can get you with a strikeout on his four-seamer, or a groundout on the sinker. Woodruff is the only starter on the top-five lists above for both four-seamers and two-seamers/sinkers -- Lugo is the only reliever with that distinction.

5) That Nationals’ Big Three is tough

The Nationals’ Big Three of Max Scherzer, Stephen Strasburg and Patrick Corbin helped lead the club to the first World Series title in franchise history. It was a strong trio, and each appeared on or near our lists. Corbin was on our xwOBA list for sliders and cutters, Scherzer just missing that list in sixth, and Strasburg second for changeups and splitters.

Corbin led the Majors in strikeouts on sliders and cutters, and the Nats had 523 such strikeouts as a team, third most among all pitching staffs. With the Nationals’ re-signing of Strasburg, the trio will be back for more in 2020, and that could spell plenty of trouble for opposing hitters, especially in the NL East.