Last season (only using Bay's Boston statistics, figured I'd grant him the extra lift they provide him just to make my point):
Manny, in his Boston days alone, had Bay beat in OPS (Manny .927 to Bay .897) and OPB (Manny .398 to Bay .370), slugging % they are virutally identical. Manny had been pretty much dogging it in Boston, and still did better in a Sox uniform in 08 than Bay did.
Manny, in his Dodger days - .489 OBP, .743 SLG%, 1.23 OPS. Annhilates Bay's numbers.
This season, 8 games in, Bay has the advantage on Manny. the only area Manny is considerably down from previous years is slugging percentage. Meaning that Manny is for the most part keeping up his impressive pace, while Bay is just off to an unreal start.