I covered something similar in a post from 2009 called Positional Hitting Over Time. I looked at how each position did in SLG relative to the league average. Here is what I said about 2B men:
"2B men started declining in the AL in the 1940s, then starting rising again in the 1960s. But even now they have not reached their earlier peak. They started declining in the 1920s in the NL but then started back up in the late 1950s."
Below are the top 25 2B men with 5000+ PAs in SLG relative to the league average. The top 4 played along time ago and it looks like 6 of the top 10 played before 1940 or mostly before 1930. The numbers are rate, the player's SLG and the league SLG. For Hornsby, we have .577/.392 = 1.47 and multiplied by 100 we get 147. The table after that uses ISO. Data from the Lee Sinins Complete Baseball Encyclopedia.
It looks like many of the power hitting 2B men played a long time ago.