Rookie Review: Is Zac Gallen Primed For A Full Breakout In 2020, Or Will He Disappoint?


Zac Gallen was thriving at Triple-A (1.77 ERA, 0.71 WHIP), exciting fantasy owners who anxiously awaited his arrival. He pitched well upon being recalled by Miami, and a surprising Trade Deadline deal to Arizona didn’t deter him. Whether it was with the Marlins or Diamondbacks, the numbers were solid:


There’s never been a question about his ability to bring swings and misses. Over 43 starts at Triple-A (ranging from 2017-2019) he posted an 11.2% SwStr% leading to a 9.94 K/9. He was even better over his 91.1 IP in ’19, watching the SwStr% balloon to 14.3% and showing that type of potential in the Majors:

  • Marlins – 12.1%
  • Diamondbacks – 13.3%

One of the keys to the surge in Arizona could be the usage of his changeup, going from 13.8% to 17.7%. That represented his best swing and miss pitch, with a 21.62% Whiff%, backing up the improvement. It also represented his best pitch to generate groundballs, with a 64.52% groundball/balls in play. That helps justify another spike that would be a huge development:

  • Marlins – 31.8%
  • Diamondbacks – 44.5%

He was at 46.2% at Triple-A prior to his recall by Miami and 42.0% overall during his time at the level. That helps to support the improvement, and while there is still likely to be home run issues pitching half his games in Arizona it should to limit the damage.

Gallen’s control is going to be one of the key conversations, after posting a 1.68 BB/9 prior to his recall. He was always solid coming up, including a 3.24 BB/9 at Triple-A in ’18. That makes the 3.71 with the Diamondbacks seem a lot more realistic, with the potential for a little bit of a further step forward.

So what does it all mean? Gallen isn’t guaranteed a spot in the Opening Day rotation, but there appears to be enough here to make an impact when his time does come. He needs to continue utilizing his changeup more, which will put him on the map for the back of your fantasy rotation. Unlikely to be an ace, he still should be a viable option in all formats. As long as you aren’t expecting his Triple-A numbers (and therefore paying a premium), there will be value.

Sources – Fangraphs, Brooks Baseball

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