For the top 4, largely pitch selection - chasing outside pitches (Teo - man has he been ugly since return; Springer with RISP - trying too hard, what is it now north of 45% K rate?; Bo just being Bo - he got better) and Vlad choosing to hit outside/up pitches (due to ump or otherwise) which leads to groundouts (2020 Vlad). Until this section gets fixed, we are going to struggle.
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For Kirk - he just couldn't get timing down, finally got it.
For Chapman - he looked lost a lot of the time (timing, no gameplan etc.) but got better and getting contact now
For Gurriel - since his stance change, he got better with pitch recognition (as intended) but looks like he lost power and timing
Tapia/Zimmer - who got way too many ABs cause of load management and injuries - pretty self-explanatory.
Montoyo - with these egregious lineups and refusing to better the lineup cause 'comfort' or some BS
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I am sure there are stats to either prove or disprove the above, but I am too lazy and the above feelycraft sounds reasonable to me