I'm hinting towards believing that I wouldn't entirely discount the Brewers (or any other organization) from trying to do whatever they can to gain a competitive edge & that Fiers hasn't been here since the current regime took over so he wouldn't have any first hand insight into what they may or may not be doing. Looking at the 2016/2017 Astros it looks like their massive improvement in K% was primarily driven by a change in personnel & playing time... Among players with at least 100 PAs, you have Colby Rasmus (417 PAs, 29.0 K%), Jason Castro (376 PAs, 32.7 K%), Luis Valbuena (342 PAs, 23.7 K%), Carlos Gomez (323 PAs, 31.0 K%), Tyler White (276 PAs, 23.6 K%), Tony Kemp (136 PAs, 19.9 K%) & Teoscar Hernandez (112 PAs, 25.0 K%) in 2016 being replaced by... Carlos Beltran (509 PAs, 20.0 K%), Brian McCann (399 PAs, 19.2 K%) & Nori Aoki (224 PAs, 12.9 K%) along with Alex Bregman (15.5 K%) & Yuli Gurriel (11.1 K%) combining for 1,190 PAs in 2017 vs only 350 PAs in 2016. League average K% at home in 2017 was 21.3 vs 22.0 on the road for a 0.7% difference. Astros K% at home in 2017 was 16.7 vs 17.9 on the road for a 1.2% difference, so it's not like they had some crazy split compared to the league as a whole.