Friday, May 23, 2014

When Stats Stabilize - Pitcher K/PA, GB%, and LD%

Since the last post on stabilization points, I've done a bit more reading on the subject and realized that FanGraphs listed different thresholds than the research they based their post on. I'm sure they have a reason for this, but when I reached out to David Temple, who referred me to Dave Cameron, I did not get an answer, so I've decided to use the information directly from the original post. It's not different to revisit my earlier post on hitter K% so I'll just do this going forward.

Today we'll look at a trio of stats for our pitchers. Strikeout, groundball, and line drive rates all purportedly stabilize for pitchers at 150 batters face and, with Collin McHugh's last start, six Astros pitchers have reached that mark. As with the last post, we'll look at this year's rates so far, last year's rates, and career rates for context. If anything jumps out, we'll see what, if anything, that player has changed in his approach to affect such changes.


K/PA

2013 K%

2014 K%

Diff

Career K%

Keuchel

18.0%

22.7%

4.7%

16.6%

Cosart

13.4%

16.4%

3.0%

14.9%

Peacock

21.1%

21.5%

0.4%

20.2%

Feldman

17.4%

12.4%

-5.0%

14.4%

Oberholtzer

15.4%

18.0%

2.6%

16.3%

McHugh

18.4%

27.0%

8.6%

18.4%

 


The two biggest standouts here are on opposite ends of the spectrum, Feldman and McHugh. I should note that for McHugh's strikeout rate, I included his time spent in the minors in 2013. If I had used just his 26 innings at the major league level, his K% would be just 8.8%.

For Feldman, the first thing that stands out is the change in his velocity and pitch selection. His sinker is averaging 89.1 mph this season, down from 90.1 mph last year. His use of the pitch has been cut nearly in half, from 31.2% of his pitches in 2013 to just 17.2% He's trying to counter this by throwing more curves, up about 12% from 2013. This curve, which had generated swings and misses about 13% of the time pretty consistently from 2011-2013 is only getting whiffs about 9% of the time this year. The biggest area of change for this is on curveballs in the zone. Just 3% of his curves thrown in the zone are getting him swinging strikes, despite him getting better movement, both horizontally and vertically, on the pitch. I'm no mechanics expert, so I couldn't tell you why his curve is more hittable this year. Perhaps the increased usage is allowing opposing hitters to sit on it more.

Collin McHugh could be a case of changing his approach. In talking with a few people and doing a bit of digging (h/t to The Crawfish Boxes contributor Brooks Parker) I've learned that pitching coach Brett Strom is a believer in the pitch tunneling philosophy. What this approach says is that a good way to hide a curveball, one of McHugh's strongest pitches, is through the use of high fastballs. Putting a fastball high in the zone gives hitters the same vertical look as a curveball, which has to start out high in order to break down through the zone. Forcing hitters to wait a hair longer to recognize the pitch makes a good curve that much better. This shows in a 7% increase in whiffs on his curve.

GB%

2013 GB%

2014 GB%

Diff

Career GB%

Keuchel

55.8%

67.7%

11.9%

56.8%

Cosart

54.5%

54.2%

-0.3%

54.4%

Peacock

36.8%

45.0%

8.2%

38.9%

Feldman

49.6%

53.3%

3.7%

47.4%

Oberholtzer

35.6%

37.0%

1.4%

36.1%

McHugh

39.8%

38.5%

-1.3%

37.7%

 


So much has been written about Keuchel the last week or two, so I won't go into it much. His sinker and change have greatly improved their ground ball rates, despite actually having less drop, because he's been able to get them lower in the zone. In fact, he's getting all of his pitches other than his cutter lower in the zone this year.

Peacock has never been considered a ground ball pitcher, so if there was going to be any change in his GB% is was going to be up. His slider, which has a ground ball rate both this year and last of over 60% has more vertical break to it so far this year and he's throwing it more often.

For McHugh, scrapping the sinker, which got over 50% groundballs over his career, has led to the small decrease in GB% but, as mentioned above, he's getting more strikeouts so it's been a pretty good tradeoff for him.

LD%

2013 LD%

2014 LD%

Diff

Career LD%

Keuchel

21.0%

12.6%

-8.4%

18.4%

Cosart

21.0%

16.3%

-4.7%

18.7%

Peacock

18.6%

18.6%

0.0%

17.6%

Feldman

18.9%

20.4%

1.5%

20.3%

Oberholtzer

21.9%

21.3%

-0.6%

21.7%

McHugh

28.2%

22.9%

-5.3%

26.1%

 


Now this is a good trend. Line drives become hits about 70% of the time so to see everyone but Feldman at or below last year's rates gives a good idea of why the rotation is as improved as they are over last year.

For Feldman, I think the answer here again lies with his curveball usage. Since both his groundball and line drive rates have gone up, that leaves his flyball rate to only go down. A pitch that drops as it reaches the hitter would have that effect on batted balls.


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