OP, I truly feel your pain. Showdown, simply and frankly, is a mess!
It needs to be completely blown up and redone.
It may say “rookie” and “vet”, but it’s really not. The pitchers and fielders are jacked up and don’t play to their ratings. They pitch and field WAY above.
50-60 rated pitchers dotting corners, a ton of “atom” balls, double plays “on demand”, relievers throwing 40+ pitches with no loss of stamina are just a few of the shenanigans you deal with.
Many of us simply skip this mode altogether.
I, personally, have only gotten two Showdowns. The starter one and WBC. After that, the few I’ve tried I’ve made it to maybe halfway.
I’ve sworn them off until SDS “fixes” them. And like you, it upsets me that this causes the grind to be much longer.