2018 Leaders Review: Top 10 September SwStr%: Regression Risks Emerge (Javier Baez, David Dahl & More)

by Eric Stashin (aka The Rotoprofessor)

We often say that September results are not indicative of what the future holds, considering that September callups help to skew the competition level.  At the same time we’ve seen it before where a late season flourish helps to point towards future success.  With that in mind, let’s take a look at the Top 10 swinging strike rates among hitters over the final month of the season to see if there are any concerns arising (especially since the pitching may not necessarily be up to typical standards):

1. Daniel PalkaChicago White Sox19.7%
2. Javier BaezChicago Cubs19.2%
3.Randal GrichukToronto Blue Jays18.1%
4.Adalberto MondesiKansas City Royals18.0%
5.Khris DavisOakland A's17.9%
6.Brandon LoweTampa Bay Rays17.8%
7.David DahlColorado Rockies16.9%
8.Scott ScheblerCincinnati Reds16.7%
9t.Stephen PiscottyOakland A's16.3%
9t.Kris BryantChicago Cubs16.3%

There are a lot of interesting names on these rankings, but let’s take a look at three of the most interesting ones:


Javier Baez – Chicago Cubs
There have always been questions about Baez’ plate discipline, and last season was no different (overall he posted a 17.9% SwStr% and 45.5% O-Swing%).  However he overcame that limitation to actually lower his strikeout rate (25.9%) and post gaudy numbers across the board (.290, 34 HR, 111 RBI, 101 R).  That said there are some obvious concerns, which we’ll dive into in much more detail, including a significant step back in his Hard% (38.8% in the first half vs. 31.8% in the second) yet he actually saw his BABIP rise (.343 to .353).

Now you couple that concern with his continued struggles to make consistent contact, with an overall Whiff% of 25.96% against breaking balls and 23.41% against offspeed pitches, and it’s easy to envision a significant falloff on the horizon.  His strikeouts appear likely to go up, which seems obvious, but the others numbers simply further cloud the issue.


Adalberto Mondesi – Kansas City Royals
You can argue that he was one of the biggest breakout performers late in the season, but there are numerous warning signs hanging out there:

  • Inability to go the other way (41.6% Pull%, 40.6% Cent%)
  • Risk of a regression in Hard% (43.1%)
  • Risk of significant rise in strikeouts (26.5%)

His September SwStr% was slightly better than his overall mark (18.2%), which is obviously a concern.  Can someone who swings and misses this much maintain a 26.5% strikeout rate?  He saw a September regression (27.7%) and it could get even worse.  At this point it’s hard to buy into the “breakout”.


David Dahl – Colorado Rockies
Dahl erupted for a big September (.287 with 9 HR), while backing it up with a 23.4% strikeout rate.  Obviously a 32.1% HR/FB is going to raise a red flag, but so is the risk in his strikeout rate (23.4% in September).  Just consider how much he struggled against all types of pitches during the month (Whiff%):

  • Hard – 16.30%
  • Breaking – 16.85%
  • Offspeed – 23.21%

How can we expect him to maintain this type of strikeout rate given those numbers?  Throw in the likely power regression as well as the potential to be viewed as a platoon player, and there should be obvious concern moving forward.

Sources – Fangraphs, Brooks Baseball

Make sure to check out all of our 2019 projections:

Date Posted
Dylan Bundy10/22/18
Foltynewicz, Mike10/09/18
Gibson, Kyle10/29/18
Hoskins, Rhys10/16/18
Hosmer, Eric11/05/18
Wheeler, Zack10/02/18

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