It has been a few years since I played the baseball sim, so sorry if everyone knows this

how does the SIM handle L/R batting splits.  Is it just done completely with an average, simulated split?

Or, I am right vaguely remembering something like after 1997 or 1998 using the actual platoon splits if there is sufficient data (50 AB?  50 PA?)

??

Nope, it's the same standard penalty/advantage for all hitters across all years. 

It's a 5% penalty for facing same-handed pitchers. 

Switch hitters are at least theoretically treated as neutral, but there are those that believe they get the 5% advantage all the time...