In real life, a batter usually gets more pitches to hit if a good hitter is behind them, while gets pitched around if there is a weaker hitter next. Does anyone know if the sim incorporates this in any way?

My first impression based on what I know would be that the sim does not incorporate this in any way, but I've started seeing enough circumstantial evidence that makes me wonder. For instance, in one progressive league, I've had a very strong offensive team for several seasons, and have noticed almost all of my hitters hit well above real life. This season, however, I've traded away some key players to invest in the future, leaving a much weaker lineup. There are still a few remaining strong hitters, and every one of them is hitting below real-life numbers. Is this totally a coincidence, or is this something built-in to the formula?

Has anyone else seen any circumstantial evidence one way or the other?

The only place I'm confident this is taken into consideration is with intentional walks. If you put Babe Ruth in front of a 200K scrub, he will get a lot more IBBs in the sim than he would in front of Lou Gehrig.

there is no such effect.

I don't think that there is any code in the sim to change performance based on lineup protection.  However, especially in progs, that doesn't mean it won't matter.  A better lineup will tire starting pitchers out faster and score more runs.  That's going to get you more plate appearances against the deeper portion of the bullpen and/or more fatigued pitchers, which is going to get your batters some easier at-bats.  That makes them look a little bit better.  I've definitely observed this effect in progs in the past.  Until it folded, I got through the first half of the '90s in a prog with Bonds, Galarraga, Paul O'Neill, Tony Phillips, Biggio, Chris Hoiles, Caminiti - a deadly lineup.  There would be 10-20 games a season where that lineup would just explode for 15+ runs after pushing the starter out early.  Everybody in the lineup probably averaged at least a hit more than they normally would in those games.  An extra 10-20 hits per season is probably about 15-30 points of batting average added on.  Add in a few walks, or at least some XBH, and it looks like a big performance improvement.

Posted by dahsdebater on 12/14/2015 2:49:00 PM (view original):
I don't think that there is any code in the sim to change performance based on lineup protection.  However, especially in progs, that doesn't mean it won't matter.  A better lineup will tire starting pitchers out faster and score more runs.  That's going to get you more plate appearances against the deeper portion of the bullpen and/or more fatigued pitchers, which is going to get your batters some easier at-bats.  That makes them look a little bit better.  I've definitely observed this effect in progs in the past.  Until it folded, I got through the first half of the '90s in a prog with Bonds, Galarraga, Paul O'Neill, Tony Phillips, Biggio, Chris Hoiles, Caminiti - a deadly lineup.  There would be 10-20 games a season where that lineup would just explode for 15+ runs after pushing the starter out early.  Everybody in the lineup probably averaged at least a hit more than they normally would in those games.  An extra 10-20 hits per season is probably about 15-30 points of batting average added on.  Add in a few walks, or at least some XBH, and it looks like a big performance improvement.

This makes sense. I'll bet that's what happened on my team. I had all-star caliber players 1-7 in the lineup for several years and my team AVG would be well over .300. Now that I've only got a couple all-star level players left, I'm seeing more realistic numbers that just happen to be a little on the low end of expectations.

Yep, I had a group of strong hitters consistently over-perform even in home games at Safeco Field for several seasons in a prog.  Dahsdebater's explanation is exactly what happened with those teams.