Something about his K rate and whiff rates is not computing. I wonder if there is still a lot of noise or luck.
2024 - A ball - 31.3% K rate and 13.8% whiff rate
2025 - A+ - 18.7% K rate and 12.8% whiff rate
The six qualified MLB players with a SwStr% between 12.6% and 12.9% last year were Adames, Cowser, Mountcastle, Suarez, McMahon, and Chisholm.
Their K rates ranged from 22.5% to 30.7%. The main variable being how aggressive they are. Mountcastle is more of a 55% swinger and he has the lower rate, Cowser is very patient with just 44% swing rate and he had the highest strikeout rate.
But Nimmala's 2024 to 2025 swing rates are within a point or two.
So I think he's getting weirdly lucky on strikeouts and isn't really exhibiting core skills that would make you think he has made a fundamental adjustment. But who knows. He is making a bit more contact and swinging a hair more often.