I've always taken it for granted that any split created with overall would have the event table apply generic historical splits as that's always been my experience - I've played a ridiculous amount of DMB. If I thought that "Overall" generated an event table was the same for lefties as righties, I'd definitely make more of an effort to project splits. The only thing I've done differently this year (though not for the first release) is regenerate tables for starting switch-hitters with strong platoon splits (like Orlando Hudson) by changing them to the side of the plate they're in tune with, regenerating the event table, and then putting them back to switch.