So far I've only been doing iron... but that's simply because I figure that as a new player, I don't have a realistic chance of getting the cards I need for the higher levels if I can't compete in the lower levels. The rosters are relatively easy to figure out at the first-pass level, since there's a lot of consensus players at many positions... but I'm pretty sure I still need to fine-tune my strategy settings. I also want to set up some kind of system for aggregating stats across multiple tournaments and teams so that I can get a proper sample size looking at which players really perform in the context of the most common opponents.
Watching at least the highlights of games, I definitely notice things that need adjusting that I wouldn't spot from the line score or even in some cases the play-by-play. One series I was constantly throwing out guys on the bases... and in the first (and so far only) tournament championship I've won, take a look at the difference in the fatigue levels between my team (on the left) and my opponent (on the right). (I don't know how much fatigue matters, but it can't help.)
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Primary team:
Secondary team, with heavy restrictions on using the auction house:
Tertiary team is AFK... I'm not allowing myself to make any changes to the team except during the offseason: