Last week, I examined pitchers who were experiencing an increase in their strikeout-minus-walk rate (K%-BB%). This week, the decliners get featured. A pitcher's K%-BB% is one of the easiest and best ways to determine a pitcher's talent, especially since the two components stabilize in a short amount of time.
| Name | Team | First Half K%-BB% | Second Half K%-BB% | Diff | NFBC OC Roster% |
|---|---|---|---|---|---|
| MacKenzie Gore | WSN | 22.7% | 8.7% | -14.0% | 63% |
| Carlos Rodon | NYY | 19.7% | 8.0% | -11.7% | 100% |
| Eduardo Rodriguez | ARI | 16.2% | 4.5% | -11.7% | 31% |
| Spencer Strider | ATL | 19.6% | 8.2% | -11.4% | 98% |
| Jake Irvin | WSN | 9.1% | 1.0% | -8.1% | 9% |
| Seth Lugo (IL) | KCR | 14.2% | 6.2% | -8.0% | 69% |
| Walker Buehler (minors) | BOS | 7.9% | 0.0% | -7.9% | 32% |
| Cal Quantrill | MIA | 12.2% | 4.3% | -7.9% | 0% |
| Ryan Gusto | HOU | 16.1% | 8.6% | -7.4% | 3% |
| Robbie Ray | SFG | 17.6% | 10.2% | -7.4% | 99% |
| Lucas Giolito | BOS | 14.6% | 7.2% | -7.3% | 99% |
| Hunter Brown | HOU | 23.4% | 16.1% | -7.2% | 100% |
| Miles Mikolas | STL | 11.4% | 4.3% | -7.1% | 3% |
| Tyler Anderson (IL) | LAA | 9.6% | 2.6% | -6.9% | 11% |
| Eury Perez | MIA | 18.2% | 11.4% | -6.8% | 96% |
| Kyle Hendricks | LAA | 10.0% | 4.2% | -5.8% | 1% |
| Eric Lauer | TOR | 20.8% | 15.1% | -5.7% | 49% |
| Slade Cecconi | CLE | 16.4% | 10.8% | -5.6% | 71% |
| Kodai Senga (minors) | NYM | 13.2% | 7.6% | -5.6% | 71% |
| Colin Rea | CHC | 12.1% | 6.6% | -5.5% | 42% |
| Andrew Heaney | PIT | 10.2% | 4.9% | -5.3% | 22% |
| Nick Pivetta | SDP | 21.4% | 16.3% | -5.1% | 100% |
Here are some notes on the most rostered pitchers.
A second half .227 BABIP (compared to career .284 BABIP) hides a ton of his issues. His strikeouts are
Last week, I examined pitchers who were experiencing an increase in their strikeout-minus-walk rate (K%-BB%). This week, the decliners get featured. A pitcher's K%-BB% is one of the easiest and best ways to determine a pitcher's talent, especially since the two components stabilize in a short amount of time.
| Name | Team | First Half K%-BB% | Second Half K%-BB% | Diff | NFBC OC Roster% |
|---|---|---|---|---|---|
| MacKenzie Gore | WSN | 22.7% | 8.7% | -14.0% | 63% |
| Carlos Rodon | NYY | 19.7% | 8.0% | -11.7% | 100% |
| Eduardo Rodriguez | ARI | 16.2% | 4.5% | -11.7% | 31% |
| Spencer Strider | ATL | 19.6% | 8.2% | -11.4% | 98% |
| Jake Irvin | WSN | 9.1% | 1.0% | -8.1% | 9% |
| Seth Lugo (IL) | KCR | 14.2% | 6.2% | -8.0% | 69% |
| Walker Buehler (minors) | BOS | 7.9% | 0.0% | -7.9% | 32% |
| Cal Quantrill | MIA | 12.2% | 4.3% | -7.9% | 0% |
| Ryan Gusto | HOU | 16.1% | 8.6% | -7.4% | 3% |
| Robbie Ray | SFG | 17.6% | 10.2% | -7.4% | 99% |
| Lucas Giolito | BOS | 14.6% | 7.2% | -7.3% | 99% |
| Hunter Brown | HOU | 23.4% | 16.1% | -7.2% | 100% |
| Miles Mikolas | STL | 11.4% | 4.3% | -7.1% | 3% |
| Tyler Anderson (IL) | LAA | 9.6% | 2.6% | -6.9% | 11% |
| Eury Perez | MIA | 18.2% | 11.4% | -6.8% | 96% |
| Kyle Hendricks | LAA | 10.0% | 4.2% | -5.8% | 1% |
| Eric Lauer | TOR | 20.8% | 15.1% | -5.7% | 49% |
| Slade Cecconi | CLE | 16.4% | 10.8% | -5.6% | 71% |
| Kodai Senga (minors) | NYM | 13.2% | 7.6% | -5.6% | 71% |
| Colin Rea | CHC | 12.1% | 6.6% | -5.5% | 42% |
| Andrew Heaney | PIT | 10.2% | 4.9% | -5.3% | 22% |
| Nick Pivetta | SDP | 21.4% | 16.3% | -5.1% | 100% |
Here are some notes on the most rostered pitchers.
A second half .227 BABIP (compared to career .284 BABIP) hides a ton of his issues. His strikeouts are down (10.2 K/9 to 8.0 BB/9) while his walks are up (3.1 BB/9 to 5.0 BB/9). The only qualified pitcher close to Rodon's 8.0 K-BB% is Kyle Hendricks at 8.6 percent.
The cause for his decline is simple: he can't find the plate. During this stretch, he had three different games with five walks, but only the Marlins made him pay. Digging through his profile, there is nothing to point to any changes besides the ability to find the plate.
Strider's been a mess this year and has gotten worse as the season has progressed. His fastball started two mph below his previous highs. Besides the loss of velocity, he hasn't been able to find the plate, with a nine percent walk rate in both halves of the season. A walk rate that high can be overlooked when a pitcher's strikeout rate is 29 percent, like Strider's was in the first half, but not 19 percent, like it was in the second.
He lost faith in his fastball, and for good reason. Over his first four seasons, the pitch had a 10 percent SwStr% or higher (13.4 percent SwStr% in 23), but it dropped to 6.7 percent this year. Batters are hitting .294/.381/.482 against it.
As he has lost faith in the fastball, his first-pitch strike rate has dropped from 62 percent to 53 percent. When he falls behind, batters hit .304/.428/.519 against him. When he's able to get that first strike, they hit .195/.244/.380.
He's trying and failing to adjust to a new norm.
For Ray, his decline is strikeout-based, with a drop from a 27 percent strikeout rate to 20 percent. Unlike Rodon, He saw his ERA jump to 4.77 (4.92 xFIP). The cause for the decline is that all his pitches have dropped in velocity.
| Pitch | First-Half Velo | Second-Half Velo | Difference |
|---|---|---|---|
| Four-Seam | 93.7 | 93.2 | -0.5 |
| Slider | 88.1 | 86.9 | -1.2 |
| Changeup | 85.5 | 84.4 | -1.1 |
| Curveball | 81.6 | 80.4 | -1.2 |
Overall, he had a 13.3 percent SwStr% in the first half and an 11.4 percent mark in the second half. It's not surprising to see a 33-year-old pitcher wear down.
An 80 percent LOB% and .244 BABIP are hiding a horrible second half (5.04 xFIP) from 31-year-old. His 7 percent K%-BB% is the fourth lowest in the second half among 68 qualified starters. For him, the decline is equal parts strikeouts (22 percent to 17 percent) and walks (seven percent to 10 percent).
The walks have taken off in the last six starts, increasing to a 13 percent walk rate. FanGraphs' two STUPH* models show his Location grades falling off. The walks are explainable.
As for the strikeouts, it's tougher to find a reason. His swinging strike rate was at 10 percent for both halves. His pitches' Stuff (i.e., strikeout ability) were also the same.
I'm concerned about his lack of command, but nothing seems to be behind the strikeout decline.
For Brown, all of his decline can be linked back to his strikeout rate dropping from 31% K% to 23% K%. Here is his average monthly fastball velocity
Month | Velocity |
|---|---|
April | 97.2 |
May | 96.5 |
June | 96.8 |
July | 96.9 |
August | 96.2 |
September | 95.5 |
He's down 1.5 mph over the season, but his September velocity is in line with last season (95.9 mph).
Even with the decline, he's still a good pitcher, just not in the discussion for the best pitcher in the game. His first K%-BB% was the fourth-best among qualified starters. In the second half, he has the 25th-highest K%-BB%. Good, not great.
While Perez has experienced a 1.5-point increase in his walk rate, his strikeout rate has dropped from 26.5 percent to 21.1 percent. I can't find any major red flags as to one reason for the decline. He lost 0.4 mph on his fastball. Maybe the decline is from his first pitch strike rate dropping from 64 percent to 54 percent. He doesn't struggle when behind in the count (.209/.323/.445), so the first strike change isn't a big deal.
One issue is that Perez started at a lower talent level compared to the other pitchers analyzed. In the first half, he posted a 4.13 xFIP, a figure which has jumped to 4.96 in the second half. He didn't have any cushion to give if his season went south.
No mixed results for Pivetta: his decline is strikeout-based, with his strikeout rate dropping from 28 percent to 23 percent. The good news? It might be over. Pivetta went through a horrible five-game stretch where his strikeout rate was down to 18 percent. In the four starts since then, he has a 30 percent strikeout rate.
During the bad five-game stretch, he moved away from this slider, a pitch with an 18 percent swinging strike rate, dropping its usage from 19 percent on the season to 13 percent and added a splitter, a pitch he ended up dumping.
After several seasons of being a good pitch, his cutter took a major step backward this year (results and STUPH metrics agree). It's not breaking down as much (about half a foot). He could take a step forward next year by ditching this bad cutter or by going back to his old one.
*I use the word STUPH as an all-encompassing term for pitch models.
