Ok, so I investigated, partially, my assumption that RHP are more advantaged. But I only looked at the top 25 RH and 25 LH pitchers with 300+ innings who played 10 or more SIM seasons, and compared real life WHIP and opponent average versus SIM WHIP and OAVE. And, turns out, for this group, I am incorrect -- they are about the same, and there is a slight advantage for LHP...
Now, because I didn't use a matching, case control method, the results aren't perfect, and they don't extend beyond the top 25 for each handedness . . . .
But, RHP had a SIM WHIP 37% higher than real life, while LHP has a SIM WHIP 34% higher than RL. Also, RHP had a SIM batting average against 25% higher, while it was 22% higher for LHP.
Now, this doesn't mean you should go out and draft LHP because the average real life WHIP and average is higher for LHP. But, at least among this sample, the bias I though existed, doesn't. If I am motivated, maybe I'll try this for some other groups of pitchers......