The top 12 of the last 30 day starting pitcher strikeout rate leaders is littered with the usual names. But of course as with any metric over an arbitrary time frame, there are a few surprising ones. Let’s discuss the four, who all happen to be 25 and under.
Last September, Jeff and I spent last September highlighting daily starters you could consider picking up for your playoffs and roto stretch run. We’ll be doing the same again this year starting with tomorrow’s super-lite 4-game slate.
(I’ll be citing the FantasyPros roster rates)
Luis Castillo – CIN v. SD (49%)
Castillo entered July with a 5.85 ERA, but has since put together a 10-start run of 3.23 ERA and 1.06 WHIP in 55.7 IP with a 26% K rate and 4% BB rate. Two 5 ER duds during the run push the ERA a bit, but he bounced back strong from each one. The Arizona one was kinda weird, too, because he bookended four perfect innings with the five runs in an inning and two-thirds.
I use xwOBA as a leading indicator of good or bad things to come mid-season, for better or for worse. It’d be good to know if such reliance is truly warranted. I further talked myself into the idea when I wrote about several underperforming hitters in early June. Many of the names therein went on some serious heaters afterward, too. It wasn’t as prescient as it was playing the odds: the hitters underperforming xwOBA most extremely through two months always, always (in the Statcast EraTM) bounce back to some degree.
It’s “predictive,” but not universally so, and only by virtue of common sense, in the same way a pitcher who allows a sub-.200 batting average on balls in play (BABIP) through two months could not reasonably sustain this high level of contact management. (There’s a discussion to be had here about the gambler’s fallacy, but I don’t think it necessarily applies to baseball. For another day.)
In terms of prior work, it’s all Baseball Prospectus‘ Jonathan Judge (only a slight exaggeration): he compared xwOBA to BP’s DRA metric as well as FIP (fielding independent pitching), a much simpler ERA estimator, and showed xwOBA is hardly superior to the field, at least for pitching. However, the article only covered year-to-year, not in-season, correlations.
After our dear and departed (but not dead) Eno Sarris asked Judge if he had looked at in-season correlations specifically, and after our dear and departed (and also not dead) Mike Petriello reinforced the notion that xwOBA could serve as an in-season predictor of regression under certain circumstances, I figured it’s high time I just tackle the question.
So: How predictive is xwOBA of wOBA in-season? For hitters and for pitchers?
I don’t really know. Thanks for reading!
When I started writing Two Good Starts, Two Bad Starts earlier this season, the idea wasn’t to point out trends in small samples so that fantasy owners could act on them right away. That is almost always a bad idea. It was to identify changes in pitcher performance that could conceivably turn into longer-term trends, which in turn could be useful guides for making roster decisions. It could have easily been called Who To Put On Your Watch List.
Now that Labor Day is behind us, there isn’t much time left for small samples to become sufficiently large samples for making decisions. Then again, if you are still in contention, roster decisions will be especially crucial going forward. If you’ve been on autopilot in starting Jon Gray every week, there’s no time like now to consider if he is potentially worth benching. Similarly, if you continue to dismiss John Gant, even as he has shaved close to a run off his ERA over the past four weeks, you may be doing so at your own risk. Or maybe not…
Read the rest of this entry »
Since returning from the disabled list (neck nerve impingement), Stephen Strasburg’s fastball velocity has dropped from averaging 96.1 mph to averaging 93.9 mph. For a pitcher known for bringing the heat, the decline immediately impacts his value going forward. The question isn’t if but how much will be the decline.
First, I completely understand Strasburg could get his fastball velocity back as soon as his next start (the chances for this could be another whole article). When determining the 30-year-old righty’s value, I needed to plant a flag at some velocity and then come up with a projection.
After striking out more than a third of opposing batters he faced during his time at Double-A and Triple-A this season, Astros prospect Joshua James finally got the call to make his Major League debut on Saturday. Given the stacked Astros rotation, it wasn’t that much of a surprise that it took until rosters expanded for James to get his chance. It turned out to be a mixed bag of a start, which is to be expected during a pitcher’s first career Major League start. But let’s rewind for a moment and learn how James got to this point.
Just shy of a month ago, on the day the Rays dealt Chris Archer to the Pirates, Thomas Bassinger of the Tampa Bay Times looked into why the hometown team’s presumed ace had put together a less-than-ace-quality season. The explanation was clear and compelling. Archer was leaving his slider out in the middle of the strike zone too often when he was facing lefties. That went a long way towards shedding light on why Archer had yielded a respectable .312 wOBA against right-handed batters but a bloated .347 wOBA against lefties in his final go-around with the Rays.
Read the rest of this entry »
At the beginning of this week, I identified and discussed a group of hitters who suffered through miserable slumps at the beginning of the season, only to return to form, or better, the rest of the way. I then did the same for some of the players who enjoyed fantastic performances in April, just to regress back to what had always been expected the rest of the way. Though this was by no means an exhaustive study, the lesson for all these players is to trust their entire body of work, not the small sample of a month.
I think this is about the time of every year that I start to realize just how long the season is and I recall the landscape in May/June and see how different it is now. I wanted to highlight a group of pitchers who have righted the ship on their season and become fantasy assets once again after being cast off.
I didn’t include David Price despite a big ERA difference (4.42 1H, 1.09 2H) because I don’t think it ever got to a point where you could realistically cut him. All of these guys were hitting waiver wires in just most mixed formats, but are now being relied on down the stretch. Some of the guys profiled actually started to turn it around before the second half, but I wanted to include them because the bulk of their emergence has come since the break.