This article is part of our The Saber's Edge series.
Pitchers three rate stats (strikeout, walk, groundball) that stabilize quickly and give us a good understand of the pitcher's ability. By concentrating on these three stats, we have a starting point for examining a pitcher in detail. The following is a look at pitchers who have changed the most in those three stats from the season's start.
When it comes to determining a pitcher's talent, strikeouts, walks and, to a lesser extent, groundball percentage, tell quite a bit about a pitcher. The importance of strikeouts and walks are easy to comprehend. Strikeouts automatically keep a runner off base and a walk automatically puts a runner on base.
With groundball rate, the answer should be simple -- more groundballs is better. In the big scheme, that idea is true, except at extreme low groundball rates. At the Hardball Times, I found that generally having a groundball rate between 35 percent and 50 percent doesn't put the pitcher at much of an advantage. The advantages really come into play with values above and below those numbers. Higher than 50 percent, the number of groundballs just begins to crowd out the number of line drives, and the groundballs are weak in nature. Under 35 percent, the pitcher begins to allow a good number of easy-to-catch popup outs.
Besides being a good measure of a pitcher's talent,
Pitchers three rate stats (strikeout, walk, groundball) that stabilize quickly and give us a good understand of the pitcher's ability. By concentrating on these three stats, we have a starting point for examining a pitcher in detail. The following is a look at pitchers who have changed the most in those three stats from the season's start.
When it comes to determining a pitcher's talent, strikeouts, walks and, to a lesser extent, groundball percentage, tell quite a bit about a pitcher. The importance of strikeouts and walks are easy to comprehend. Strikeouts automatically keep a runner off base and a walk automatically puts a runner on base.
With groundball rate, the answer should be simple -- more groundballs is better. In the big scheme, that idea is true, except at extreme low groundball rates. At the Hardball Times, I found that generally having a groundball rate between 35 percent and 50 percent doesn't put the pitcher at much of an advantage. The advantages really come into play with values above and below those numbers. Higher than 50 percent, the number of groundballs just begins to crowd out the number of line drives, and the groundballs are weak in nature. Under 35 percent, the pitcher begins to allow a good number of easy-to-catch popup outs.
Besides being a good measure of a pitcher's talent, the three stats stabilize quickly in a season. Of the most common stats, they are some of the fastest to stabilize. It takes about 70 batters faced for groundball rate (GB%) and strikeout rate (K%) to stabilize. Walk rate (BB%) takes a little longer at 170 batters faced. For reference, the hero for us overweight 40-year-olds, Bartolo Colon, has already faced 127 batters this season. We are at the point in the season when a pitcher has thrown enough, so we know who he will likely the rest of the season.
This week, I will look for pitchers who have changed some combination of the three stats the most from the second half of 2015 to 2016. I limited the search to just pitchers who have thrown more than 20 innings, so most relievers aren't included. For the final change value, I used the absolute change in K% and BB% and half the change in GB%. A pitcher's groundball rate can change quite a bit, so I wanted to lessen the effect. The pitcher's true groundball rate is correct in the GB% column.
| PLAYER | K% | BB% | GB% | TOTAL CHANGE |
| Yordano Ventura | -6.5 | 8.0 | -11.8 | 20.5 |
| Rubby De La Rosa | 12.5 | -2.2 | 8.3 | 18.7 |
| Brandon Finnegan | -6.6 | 4.5 | -11.6 | 16.9 |
| Stephen Strasburg | -8.2 | 2.6 | 12.2 | 16.9 |
| Dallas Keuchel | -8.5 | 6.7 | -2.6 | 16.5 |
| Chris Young | 5.2 | -3.7 | 12.8 | 15.4 |
| Kyle Gibson | -8.1 | 3.7 | 6.6 | 15.1 |
| Hector Santiago | 2.4 | -4.2 | 16.8 | 15.0 |
| Matt Harvey | -8.8 | 3.7 | -4.8 | 14.8 |
| Taylor Jungmann | -10.0 | 1.9 | 5.9 | 14.8 |
| Raisel Iglesias | -5.6 | -1.5 | -14.8 | 14.5 |
| Bud Norris | -11.1 | 2.1 | -2.3 | 14.3 |
| Carlos Carrasco | -9.0 | -1.0 | -8.4 | 14.3 |
| Doug Fister | -6.1 | 3.6 | -8.8 | 14.2 |
| Sonny Gray | 4.0 | 4.1 | 11.9 | 14.1 |
| Chris Tillman | 8.6 | 0.6 | -9.7 | 14.1 |
| Shelby Miller | -2.7 | 6.9 | -8.8 | 14.0 |
| Danny Salazar | 6.6 | 5.1 | 4.6 | 14.0 |
| Marco Estrada | 7.1 | 3.5 | 6.0 | 13.6 |
| Jose Quintana | 6.5 | 1.9 | -10.1 | 13.5 |
| Jeff Locke | 0.1 | 6.3 | 13.4 | 13.0 |
| Mike Pelfrey | -2.9 | 7.8 | 4.1 | 12.8 |
| Matt Shoemaker | -7.5 | 2.0 | -6.3 | 12.7 |
| Drew Pomeranz | -0.7 | 7.4 | 9.1 | 12.6 |
| Kris Medlen | 1.3 | 10.4 | -1.4 | 12.4 |
| Johnny Cueto | 8.4 | -1.9 | 4.2 | 12.4 |
| Erasmo Ramirez | 4.6 | -2.8 | 9.9 | 12.3 |
| Nicholas Tropeano | -2.8 | 4.1 | -10.5 | 12.1 |
| Mike Fiers | -6.6 | -5.2 | -0.2 | 11.9 |
| Matt Moore | 9.0 | -2.2 | 1.3 | 11.9 |
| Jhoulys Chacin | 6.1 | -4.7 | 1.8 | 11.6 |
| Hisashi Iwakuma | -4.5 | 2.6 | -8.9 | 11.6 |
| Anibal Sanchez | 4.2 | 7.1 | -0.5 | 11.6 |
| Kyle Hendricks | -5.2 | -3.3 | 6.0 | 11.5 |
| Martin Perez | -2.8 | 5.1 | -7.1 | 11.5 |
| Jaime Garcia | 7.4 | 3.9 | -0.2 | 11.4 |
| Tanner Roark | 4.9 | 3.0 | 7.0 | 11.4 |
| Taijuan Walker | 2.7 | -2.3 | 12.5 | 11.3 |
| Noah Syndergaard | 5.8 | -0.5 | 9.7 | 11.1 |
| Collin McHugh | -5.0 | -1.9 | -8.2 | 11.0 |
| J.A. Happ | -9.5 | 0.3 | -2.4 | 11.0 |
| Francisco Liriano | -2.1 | 3.8 | 10.2 | 10.9 |
| Mat Latos | -6.6 | 2.1 | -4.5 | 10.9 |
| Matt Wisler | 3.8 | -2.0 | 10.1 | 10.9 |
| Max Scherzer | -6.7 | 2.7 | 1.8 | 10.3 |
| Cole Hamels | -2.4 | 5.4 | 5.1 | 10.3 |
| Bartolo Colon | 7.7 | -1.2 | -2.3 | 10.0 |
| Rich Hill | -3.6 | 4.9 | 2.9 | 10.0 |
| Jeff Samardzija | 3.7 | 0.8 | 10.5 | 9.8 |
| Aaron Nola | 7.8 | -1.2 | -1.2 | 9.6 |
| Jose Fernandez | 3.8 | 5.3 | -0.6 | 9.4 |
| Jake Arrieta | -3.5 | 2.0 | -7.8 | 9.4 |
| Michael Pineda | 4.4 | 2.9 | -4.0 | 9.4 |
| R.A. Dickey | 2.5 | 5.1 | 3.5 | 9.4 |
| Jorge De La Rosa | 4.9 | 2.1 | -4.6 | 9.3 |
| Ian Kennedy | -4.5 | 1.5 | -6.6 | 9.2 |
| Drew Smyly | 5.6 | -3.3 | 0.4 | 9.2 |
| Madison Bumgarner | -0.7 | 4.1 | -8.6 | 9.1 |
| Nathan Eovaldi | 3.8 | -3.2 | -3.8 | 8.8 |
| Jeremy Hellickson | 6.0 | 0.2 | -5.3 | 8.8 |
| Felix Hernandez | -1.1 | 7.0 | 1.4 | 8.8 |
| James Shields | -6.8 | -1.7 | 0.7 | 8.8 |
| Jered Weaver | -4.3 | 0.8 | -7.4 | 8.8 |
| Steven Matz | 3.3 | 2.5 | 5.9 | 8.7 |
| Masahiro Tanaka | 1.4 | 0.7 | 12.9 | 8.6 |
| Cody Anderson | 1.6 | -4.0 | -5.5 | 8.4 |
| Chris Sale | -6.9 | 0.6 | 1.6 | 8.4 |
| Tommy Milone | 2.8 | 1.8 | 7.5 | 8.4 |
| Aaron Sanchez | 3.3 | 0.7 | -8.1 | 8.0 |
| Chase Anderson | -4.7 | 1.9 | 2.4 | 7.8 |
| Scott Feldman | 3.3 | 4.0 | 0.9 | 7.7 |
| Tom Koehler | -3.7 | 0.8 | -6.4 | 7.7 |
| John Danks | -0.5 | 2.5 | -9.3 | 7.6 |
| Gio Gonzalez | -3.9 | -2.3 | -2.6 | 7.5 |
| Jon Niese | 3.8 | 0.1 | -6.6 | 7.3 |
| Edinson Volquez | 1.8 | -1.2 | 8.4 | 7.2 |
| Zack Greinke | -5.7 | -0.5 | -1.9 | 7.1 |
| Wade Miley | -1.6 | -2.4 | -5.9 | 6.9 |
| Garrett Richards | 0.7 | 0.9 | -10.4 | 6.9 |
| Adam Conley | 3.3 | 3.5 | -0.1 | 6.8 |
| Jordan Zimmermann | -5.1 | 0.1 | 3.0 | 6.8 |
| Chris Bassitt | -2.0 | 2.7 | -3.8 | 6.7 |
| Gerrit Cole | -2.3 | 4.2 | 0.1 | 6.6 |
| Vincent Velasquez | 4.7 | 1.1 | -1.5 | 6.6 |
| Ubaldo Jimenez | 4.2 | 2.3 | 0.1 | 6.6 |
| Chris Archer | 2.2 | 0.9 | -6.9 | 6.5 |
| Corey Kluber | 0.3 | -1.1 | 10.3 | 6.5 |
| Ervin Santana | 3.4 | 1.7 | 2.4 | 6.3 |
| Chad Bettis | -2.4 | -2.4 | -2.7 | 6.2 |
| Rick Porcello | 4.9 | -0.3 | 1.8 | 6.0 |
| Jerad Eickhoff | 1.1 | -2.5 | 4.7 | 5.9 |
| Derek Holland | -1.5 | -0.2 | -8.4 | 5.8 |
| Jon Lester | -1.1 | 0.8 | -7.6 | 5.7 |
| Clayton Kershaw | -3.3 | -2.0 | 0.4 | 5.5 |
| Michael Wacha | -1.1 | -3.2 | 2.2 | 5.4 |
| Scott Kazmir | 2.3 | -0.8 | 4.3 | 5.2 |
| Jake Peavy | -2.2 | 1.8 | 1.7 | 4.9 |
| Wei-Yin Chen | 1.3 | 0.2 | 6.7 | 4.8 |
| Matt Cain | 3.0 | 1.2 | -1.3 | 4.8 |
| Joe Ross | -3.6 | -0.1 | -2.2 | 4.7 |
| Alex Wood | -0.3 | 1.2 | 6.5 | 4.7 |
| Carlos Rodon | 0.0 | -0.3 | 8.4 | 4.6 |
| Justin Verlander | 1.4 | 2.8 | -0.4 | 4.4 |
| CC Sabathia | -3.1 | 0.8 | 1.0 | 4.3 |
| Jake Odorizzi | -0.6 | -2.5 | 2.1 | 4.2 |
| John Lackey | 0.2 | 0.9 | -6.1 | 4.2 |
| Juan Nicasio | 1.6 | -2.0 | -0.8 | 4.0 |
| Marcus Stroman | -0.9 | 0.7 | -4.7 | 4.0 |
| Kendall Graveman | 2.8 | -0.9 | -0.2 | 3.8 |
| Colby Lewis | -0.6 | 3.0 | 0.2 | 3.7 |
| Wily Peralta | 2.3 | -0.3 | 2.2 | 3.7 |
| Carlos Martinez | -1.9 | -0.4 | -2.4 | 3.5 |
| Andrew Cashner | -0.6 | -0.2 | -5.1 | 3.3 |
| Jason Hammel | -0.6 | 1.4 | 2.5 | 3.2 |
| Steven Wright | 0.6 | -1.0 | 3.0 | 3.2 |
| Mike Leake | 1.3 | 0.1 | -3.5 | 3.1 |
| David Price | 1.6 | -0.2 | -2.6 | 3.1 |
| Jimmy Nelson | -0.4 | 1.6 | 1.5 | 2.8 |
| Nate Karns | -0.9 | 1.0 | 1.3 | 2.6 |
| Julio Teheran | 0.0 | -1.0 | 0.7 | 1.4 |
Yordano Ventura
Wow, a bunch of changes and none for the better. Every stat is heading in the wrong direction and a reasonable 3.67 ERA (supported by a .203 BABIP) is hiding the changes with all his ERA estimators higher than 5.00. One obvious change is a drop in velocity of ~1.5 mph. This drop explains the drop in strikeouts, but what about the rest of the numbers.
Digging through his detailed stats, it seems like hitters aren't chasing his curve and change. If they are out of the zone, hitters are just letting them go by. I wonder if hitters are able to tell the difference between his pitches from his delivery. The other item of note, the drop in ground balls is because he has moved from using his sinking two-seamer from 29 to 18 percent of the time.
Rubby De La Rosa
Rubby is moving in the exact opposite direction of Ventura. De La Rosa is seeing his strikeouts and groundball rates jump while his walk rate is generally constant to down. The difference isn't from a velocity uptick with his velocity staying constant. The key is the new Warthen slider he started throwing last year. He has started using it instead of his changeup to gets hitters out. I will let BrooksBaseball.net describe his slider so far this season:
"His slider generates an extremely high number of swings and misses compared to other pitchers' sliders, is a real worm killer that generates an extreme number of groundballs compared to other pitchers' sliders, is much harder than usual and has primarily 12-6 movement. New pitch mix with great results and it looks like he can keep the results. I would be buying him in all leagues at this point."
Brandon Finnegan
Most of Finnegan's changes are from moving from a reliever to a starter. I would ignore the changes for now as he sets up a new base level of production.
Stephen Strasburg
Strasburg is seeing some normal aging with his strikeouts going down and walks up. Two things are controlling his change. First, he went off last September with a 43-percent K rate. No starter has ever kept up those numbers, so some regression is expected. The second change is the 10-percent point jump in his groundball rate from 42 to 52 percent. This jump has helped to keep his HR/9 at 0.25 and his HR/FB at 4 percent. Like De La Rosa, Strasburg's increase in groundball rate comes from changing his pitch mix. First, he has all but ditched his two-seamer, which didn't even produce ground balls at a decent rate (40 percent). Instead, he has been using a slider, which is getting 60 percent groundballs. Besides the slider, his change (92 percent ... yes, that is 92 percent) and curve (67 percent) are getting groundballs at a way above average clip.
Dallas Keuchel
Keuchel has been a decent pitcher until last season when he was able to ramp up the strikeouts and have a Cy Young season. This season, the strikeouts are down probably because of a near 2-mph drop in velocity. This decline should not be the causing the struggles he is seeing. Over the same time, his walk rate has doubled (6 to 11 percent) to a career high. His K%-BB% has moved from the Chris Sale to Chris Bassitt territory. His only saving grace this season is he is keeping his home runs down (0.24 HR/9) with his 56 percent GB rate. Keuchel can be a good pitcher with a lower strikeout rate, but he has to get the walks immediately under control.
Julio Teheran, Nate Karns, Jimmy Nelson and the rest at the end of the rankings
Seeing a pitcher down here means one thing, they haven't inherently changed and their production and should be about the same as last year. Staying the same can could be good or bad depending on the pitcher's production.
At this point in the season, owners should be getting a good idea of a pitcher's seasonal talent level. By using strikeout, walk and groundball rates, owners can see which way these pitchers are headed. Hopefully, I was able to point out some pitchers on the move. Let me know if you have any other questions on any other pitchers in the above list.
