I changed my mind. Stadiums don't matter. All 6 division winners in a recent league I'm in were better on the road!

I think drafting well is the most important thing. If you have a crud team, it will suck, no matter how well you manage it.

That being said, I do think micromanaging can earn several more wins per year (how many? hard to say).

When you have time to look at your opponent's

A) rotation for a series (which is rarely changed),
B) lineup (particularly the 'type' of players they have),
C) and consider the park the games are in,

you can often determine the best pitchers to select each game for your team. If you have a crud guy at the back end of the rotation, you're able to use him predominately in pitcher's parks, which can make a marked difference. You can also match him up against your opponent's worst pitcher, which gives you a better shot at winning when he's on the mound.

You're also able to pick which games you should rest players, etc by doing this. Furthermore, changing team base running aggressiveness & steal settings for individual players to match the opponent's defense can also make a big difference.

That being said, it's difficult to micromanage a team all year. You have to log on 3X a day to examine your opponent's team, and keep track of where in the rotation your next opponent is (meaning the next series) , as well as the park for the current & next series. It's fun, but time consuming, and not really feasible most of the time.

I miss the college days when I actually had time to do that.  Sad thing is, I'd spend time making random changes to my lineup trying to fix things, rather than look at matchups and examining my opponent for weaknesses.

mee too Jstops, and speaking of managing... I need help with a team I may create for an OL.  Would my offense survive if Mr. 95 Boggs batted 3rd for most of the year?

Actually Boggs will be batting #2 in front of "The Bird Man," Birdie Cree. Maybe the better question is will I survive spending only 34 mil on Offense and 45 on Pitching?

"Management" won't necessarily win you a pennant, but it can win you a WS.

Intereting thread.  I'm a newbie at this game and I think I've noticed a few trends among people who win and based on some experimenting have noticed some trends with my own team as well.  Certainly there are a lot of aspects to this game that are important if you want to win.  I think the team you draft is very important. I've only played in $80 million cap and a $100 million cap and it seems that at this level you want SPEED on offense. Power doesn't help all that much. It's almost as if in these cap leagues we are playing in the old 1880-1920 era when speed and 400 inning eater starting pitchers were king.  I can't say what wins in leagues with higher caps but I'm guessing power and a strong and diverse bench comes into play.

I think you can also OVER GM. Some guys talked about over managing, which may be  true (especially in Live games) but I think making too many GM moves too often can screw with your team. Much like it could in real life, making a lot of changes to a team could affect the people on the team. I don't know how smart the simulator is, but it seems pretty smart.  If a guy gets waived because he had a few bad outings, perhaps that affects other players on the team.

I do look at the matchups.  If a catcher I'm playing has a weak throwing arm, I'm going to be very aggressive on the basepaths. If I'm facing a pitcher with a low ERA, I might opt to hit and run more often, especially if the catcher has a strong throwing arm.  Or, depending on if my team is hitting well lately, maybe I don't hit and run. 
One aspect I wonder if some of you veterans can comment on is the Performance History.  Do you think past performance in SimLeague matters for the players?  Should you consider that much when drafting?  Also, what if a guy you have who is normally say a .280 hitter and hits 20 homers in a season and steals 50 bases for the season you picked him (in other words a leadoff hitter type or #2 hitter type) is on a tear and starts the season hitting .350 and hitting with a lot of power. Do you move him into a cleanup role even though he is more of a leadoff hitter in real life? Thanks in advance.