Not entirely, but a start ... also look at the ballpark construction trend during that time ... and note that 22 of the 30 opened new stadiums since 1991. Teams in the early part of the trend were shifting from multipurpose monstrosities to Camden Yards sort of bandboxes. To wit, the Orioles going from Memorial Stadium to Camden Yards, the Reds going from Riverfront to Great American, the Pirates going from Three Rivers to PNC, the Astros going from the Astrodome to Minute Maid Park. Only really Seattle went the other way (Kingdome to Safeco) and San Francisco stayed about the same. And let's not even discuss Coors Field. Since the middle of the last decade the new stadiums with the notable exception of Yankee Stadium have involved teams going the other way, (Qualcomm to Petco, Busch Stadium, Metrodome to Target Field, Shea to Citi Field) to much more pitching oriented layouts. That impact cannot be ignored.
I am not discounting that PEDs had some impact - but given a sport where such specialized skills are involved, I have no way of guessing exactly how much of an impact it DID have (not what the players or media THINK happened). And there are other external factors.