Here's yet another way of looking at the effect of the Steroids Era. When a team scores exactly 5 runs, they win more often than they lose. That's always been true. But check out the team winning percentage when scoring exactly 5 runs over the last 25 years:
In the late 1980s (save the whacked out homer-happy 1987), five runs meant nearly a 70% chance of winning. But then the juice kicked in and there was a rapid decline in 5-run-winning-percentage in the mid 1990s. The valley was in 1996, when teams scoring exactly 5 runs won only 55% of the time.
After offense peaked in 2001, the win percentage went back on the rise, continuing mainly upwards through 2011, when teams scoring exactly 5 runs won 65% of the time.
That difference--55% in 1996 vs 65% in 2011--might not sound like a lot, but consider this: a team that finishes the season with a .550 winning percentage has gone 89-73 while a team that finishes at .650 has gone 105-57. That's the difference between a team with a shot at the wild card and a runaway winner for the best record in baseball.