Eh, well, the reason the Rockies haven't had a big time power hitter is they usually have had quality, "moderately" controlled players at 1B, LF and RF. Do you swap a pre-60 HR Sosa for Bichette? Is a pre-2000 Bonds really worth 10 million more a year than Bichette? Is a Helton (especially a young Helton) or a Galarraga really much worse than a McGwire?

Basically, for the Rockies to have a 50HR Hitter, you'd need to find a 2B or 3B who hits 50 home runs or the Rockies would need an elite prospect to come out of their own ranks that plays a position other than SS.

Maybe altitude plays into it a bit too.. it's hard to be a slow, "big-bodied" slugger in Denver's thin air. Also, Coors has a pretty big outfield so the Rockies would lean more towards people who can run a bit. That narrows down the types of rookies that might make it to the majors.