Thanks for the ideas
Pitcher fatigue could be part of my problem but I'm not sure. I usually try to keep my good starters in for at least a little bit longer as I've found that HAL can get a little trigger-happy at times and pull them early. Sometimes I use slow hook and other times I adjust the fatigue settings. In theory, if it's a 10-12M pitcher it should be a reasonable decision I would think. Overall I'm doing decently well but the one-run games can be a problem. I currently have Jake Arietta 11M 7* set to slow hook and in 17.1 innings he gave up 18 runs and my park is 8 8 0 0. I'm sure this is mostly just bad luck but slow hooking him may have been a mistaken. Extremely small sample size though.
As for relievers I'd say I spend about an average amount vs what other players spend. I avoid anyone expensive such as 3M+ but will splurge a bit for elite specialists at times (close to 2M). Generally speaking I think my pitching is usually good. I'm also very biased toward 1 rated defenders and strong arms so my defense tends to be elite. However at times it almost seems like defense doesn't matter as the platoon teams with all 3s and 4s and average pitching feel impossible to score runs against. Sometimes it's just confusing
As for defensive replacements I stopped using them because they come in in the 7th inning and really hamper my offense. I've found that in practice what often happens is they enter the game and the opponent scores and now I'm behind with a weaker offense. That said I do generally have very strong defense to begin with so my situation may be a bit different.