Breakout or Bust: Is David Dahl’s September Explosion A Sign Of Things To Come? Don’t Be So Sure…

by Eric Stashin (aka The Rotoprofessor)

A long time ago in a galaxy far, far away…  OK, maybe things aren’t quite that bad but it felt like the Rockies’ David Dahl had become a forgotten man.  There was a time that he was considered to be among the elite prospects in the game, but injuries and a crowded outfield had seemingly made him forgettable.  That was until 2018, and more specifically September, when he exploded and put his name back on the map.

First let’s look at the overall numbers from last year:

249 At Bats
.273 Batting Average (68 Hits)
16 Home Runs
48 RBI
31 Runs
5 Stolen Bases
.325 On Base Percentage
.534 Slugging Percentage
.311 Batting Average on Balls in Play

His late season surge included a five-game home run streak, helping him to hit .275 with 9 HR and 27 RBI in September.  Can he maintain that type of performance?  Is he a can’t miss option for the upcoming season?  We won’t have all of the answers until the offseason plays itself out (because his playing time remains no guarantee), but we can at least start getting a perception.



There’s no questioning his power, but can we expect him to maintain the 32.1% HR/FB he posted in 87 September AB?  That alone is going to raise a red flag, as does his clear decision to try and hit for more power.  His fly ball rate rose significantly, to 42.4%, after posting the following marks at Triple-A over the past three seasons:

  • 2016 (68 PA) – 36.9%
  • 2017 (74 PA) – 32.7%
  • 2018 (78 PA) – 37.5%

Again it’s not to say that he won’t provide power, but it’s more realistic to expect something in the 25-30 HR range as opposed to an “elite” mark.  That’s not going to knock him off radars, obviously, just know the truth.



Even as he was emerging last season the left-handed hitter showed a reason to believe that he was going to be subject to a platoon moving forward:

  • RHP – .286/.346/.568
  • LHP – .234/.258/.438

That’s another red flag, especially with consistent battles with the Dodgers (and their slew of left-handed hitters).



This is where things really get questionable.  While his strikeout rate was 25.1% last season, the underlying metrics gave a much uglier perception:

  • SwStr% – 15.4%
  • O-Swing% – 39.6%

It wasn’t just one type of pitch that he struggled with either, giving that much more reason to pause (Whiff%):

  • Hard – 17.74%
  • Breaking – 13.68%
  • Offspeed – 20.28%



He has power potential, but it may not be quite as high as you are dreaming today.  Couple that regression with the potential spike in strikeouts and there’s obvious risk in terms of his batting average.  Yes a 37.7% Hard% gives him a little bit more leeway, but he also was pull happy (45.4%) and that will make him prone to shifts as well.

If we told you that he was going to likely be a .245 hitter with 27 HR, would you go crazy to acquire him?  There’s value and upside, but you also don’t want to make the mistake of overvaluing him come draft time.  Chances are the name and a strong September cause his value to balloon far past the actual performance.

Sources – Fangraphs, Brooks Baseball


  1. Mitch says:

    What about Dahl’s speed? I know he didn’t run much last year but coming up through the minors wasn’t he more known for his speed then his power?

    • Rotoprofessor says:

      At this point I don’t think you can expect him to be a difference maker with speed (especially given his injury history). He’ll chip in a few SB, but probably not enough to sway you

  2. Charles Stevens says:

    This guy screams Randal Grichuk to me

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